Addressing Behavioral Barriers to COVID-19 Testing With Health Literacy–Sensitive eHealth Interventions: Results From 2 National Surveys and 2 Randomized Experiments

Background Polymerase chain reaction (PCR) testing for COVID-19 was crucial in Australia’s prevention strategy in the first 2 years of the pandemic, including required testing for symptoms, contact with cases, travel, and certain professions. However, several months into the pandemic, half of Australians were still not getting tested for respiratory symptoms, and little was known about the drivers of and barriers to COVID-19 PCR testing as a novel behavior at that time. Objective We aimed to identify and address COVID-19 testing barriers, and test the effectiveness of multiple eHealth interventions on knowledge for people with varying health literacy levels. Methods The intervention was developed in 4 phases. Phase 1 was a national survey conducted in June 2020 (n=1369), in which testing barriers were coded using the capability-opportunity-motivation-behavior framework. Phase 2 was a national survey conducted in November 2020 (n=2034) to estimate the prevalence of testing barriers and health literacy disparities. Phase 3 was a randomized experiment testing health literacy–sensitive written information for a wide range of barriers between February and March 2021 (n=1314), in which participants chose their top 3 barriers to testing to view a tailored intervention. Phase 4 was a randomized experiment testing 2 audio-visual interventions addressing common testing barriers for people with lower health literacy in November 2021, targeting young adults as a key group endorsing misinformation (n=1527). Results In phase 1, barriers were identified in all 3 categories: capability (eg, understanding which symptoms to test for), opportunity (eg, not being able to access a PCR test), and motivation (eg, not believing the symptoms are those of COVID-19). Phase 2 identified knowledge gaps for people with lower versus higher health literacy. Phase 3 found no differences between the intervention (health literacy–sensitive text for top 3 barriers) and control groups. Phase 4 showed that a fact-based animation or a TikTok-style video presenting the same facts in a humorous style increased knowledge about COVID-19 testing compared with government information. However, no differences were found for COVID-19 testing intentions. Conclusions This study identified a wide range of barriers to a novel testing behavior, PCR testing for COVID-19. These barriers were prevalent even in a health system where COVID-19 testing was free and widely available. We showed that key capability barriers, such as knowledge gaps, can be improved with simple videos targeting people with lower health literacy. Additional behavior change strategies are required to address motivational issues to support testing uptake. Future research will explore health literacy strategies in the current context of self-administered rapid antigen tests. The findings may inform planning for future COVID-19 variant outbreaks and new public health emergencies where novel testing behaviors are required. Trial Registration Australian New Zealand Clinical Trials Registry ACTRN12621000876897, https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=382318 ; Australian New Zealand Clinical Trials Registry ACTRN12620001355965, https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=380916&isReview=true

Manuscript tracking number * If this is a JMIR submission, please provide the manuscript tracking number under "other" (The ms tracking number can be found in the submission acknowledgement email, or when you login as author in JMIR. If the paper is already published in JMIR, then the ms tracking number is the four-digit number at the end of the DOI, to be found at the bottom of each published article in JMIR) Identify the mode of delivery. Preferably use "web-based" and/or "mobile" and/or "electronic game" in the title. Avoid ambiguous terms like "online", "virtual", "interactive". Use "Internet-based" only if Intervention includes non-web-based Internet components (e.g. email), use "computer-based" or "electronic" only if o�ine products are used. Use "virtual" only in the context of "virtual reality" (3-D worlds). Use "online" only in the context of "online support groups". Complement or substitute product names with broader terms for the class of products (such as "mobile" or "smart phone" instead of "iphone"), especially if the application runs on different platforms.
Does your paper address subitem 1a-i? * Copy and paste relevant sections from manuscript title (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study Multi-phase project reported in the paper, so not limited to web-based intervention

1a-ii) Non-web-based components or important co-interventions in title
Mention non-web-based components or important co-interventions in title, if any (e.g., "with telephone support").
subitem not at all important 1 2 3 4 5 essential 1b) ABSTRACT: Structured summary of trial design, methods, results, and conclusions NPT extension: Description of experimental treatment, comparator, care providers, centers, and blinding status.
Does your paper address subitem 1a-ii?
Copy and paste relevant sections from manuscript title (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study Multi-phase project reported in the paper, so not limited to intervention but also surveys 1a-iii) Primary condition or target group in the title Mention primary condition or target group in the title, if any (e.g., "for children with Type I Diabetes") Example: A Web-based and Mobile Intervention with Telephone Support for Children with Type I Diabetes: Randomized Controlled Trial Does your paper address subitem 1a-iii? * Copy and paste relevant sections from manuscript title (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study subitem not at all important 1 2 3 4 5 essential 1b-i) Key features/functionalities/components of the intervention and comparator in the METHODS section of the ABSTRACT Mention key features/functionalities/components of the intervention and comparator in the abstract. If possible, also mention theories and principles used for designing the site. Keep in mind the needs of systematic reviewers and indexers by including important synonyms. (Note: Only report in the abstract what the main paper is reporting. If this information is missing from the main body of text, consider adding it) Does your paper address subitem 1b-i? * Copy and paste relevant sections from the manuscript abstract (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study "The intervention was developed through 4 phases. Phase 1 was a national survey in June 2020 (n=1369), where testing barriers were elicited and coded using the COM-B framework (capability-opportunity-motivation-behavior). Phase 2 was a national survey in November 2020 (n=2869) to estimate prevalence of testing barriers and health literacy disparities. Phase 3 was a randomised experiment testing health literacy-sensitive written information for a wide range of capability/motivation barriers in February-March 2021 (n=1314), where participants chose their top 3 barriers to testing to view a tailored intervention. Phase 4 was a randomised experiment testing 2 audio-visual interventions addressing common testing barriers for people with lower health literacy in November 2021, targeting young adults as a key group endorsing misinformation (n=1527)." subitem not at all important 1 2 3 4 5 essential 1b-ii) Level of human involvement in the METHODS section of the ABSTRACT Clarify the level of human involvement in the abstract, e.g., use phrases like "fully automated" vs. "therapist/nurse/care provider/physician-assisted" (mention number and expertise of providers involved, if any). (Note: Only report in the abstract what the main paper is reporting. If this information is missing from the main body of text, consider adding it) Does your paper address subitem 1b-ii?
Copy and paste relevant sections from the manuscript abstract (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study "Phase 3 was a randomised experiment testing health literacy-sensitive written information for a wide range of capability/motivation barriers in February-March 2021 (n=1314), where participants chose their top 3 barriers to testing to view a tailored intervention. Phase 4 was a randomised experiment testing 2 audio-visual interventions addressing common testing barriers for people with lower health literacy in November 2021, targeting young adults as a key group endorsing misinfotmation (n=1527)." subitem not at all important 1 2 3 4 5 essential 1b-iii) Open vs. closed, web-based (self-assessment) vs. face-to-face assessments in the METHODS section of the ABSTRACT Mention how participants were recruited (online vs. o�ine), e.g., from an open access website or from a clinic or a closed online user group (closed usergroup trial), and clarify if this was a purely web-based trial, or there were face-to-face components (as part of the intervention or for assessment). Clearly say if outcomes were self-assessed through questionnaires (as common in web-based trials). Note: In traditional o�ine trials, an open trial (open-label trial) is a type of clinical trial in which both the researchers and participants know which treatment is being administered. To avoid confusion, use "blinded" or "unblinded" to indicated the level of blinding instead of "open", as "open" in web-based trials usually refers to "open access" (i.e. participants can self-enrol). (Note: Only report in the abstract what the main paper is reporting. If this information is missing from the main body of text, consider adding it) Does your paper address subitem 1b-iii?
Copy and paste relevant sections from the manuscript abstract (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study subitem not at all important 1 2 3 4 5 essential 1b-iv) RESULTS section in abstract must contain use data Report number of participants enrolled/assessed in each group, the use/uptake of the intervention (e.g., attrition/adherence metrics, use over time, number of logins etc.), in addition to primary/secondary outcomes. (Note: Only report in the abstract what the main paper is reporting. If this information is missing from the main body of text, consider adding it) Does your paper address subitem 1b-iv?
Copy and paste relevant sections from the manuscript abstract (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study "The intervention was developed through 4 phases. Phase 1 was a national survey in June 2020 (n=1369), where testing barriers were elicited and coded using the COM-B framework (capability-opportunity-motivation-behavior). Phase 2 was a national survey in November 2020 (n=2869) to estimate prevalence of testing barriers and health literacy disparities. Phase 3 was a randomised experiment testing health literacy-sensitive written information for a wide range of capability/motivation barriers in February-March 2021 (n=1314), where participants chose their top 3 barriers to testing to view a tailored intervention. Phase 4 was a randomised experiment testing 2 audio-visual interventions addressing common testing barriers for people with lower health literacy in November 2021, targeting young adults as a key group endorsing misinformation (n=1527)." CONSORT-EHEALTH (V 1.6.1) -Submission/Publication Does your paper address subitem 1b-v?
Copy and paste relevant sections from the manuscript abstract (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study "In Phase 1, barriers were identified in all three categories of the COM-B model: capability (e.g. understanding which symptoms to test for), opportunity (e.g. not being able to access a PCR test), and motivation (e.g. not believing the symptoms could be COVID-19). Phase 2 found knowledge gaps for people with lower vs higher health literacy. Phase 3 found no differences between the intervention (health literacy-sensitive text using a wide range of barriers) and control groups. Phase 4 used a shorter intervention and showed that a factbased animation, or a Tiktok video intervention presenting the same facts in a humorous style, increased knowledge about COVID-19 testing compared to government information. However, no differences were found for COVID-19 testing intentions." subitem not at all important Does your paper address subitem 2a-ii? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study "The behaviour of individuals has been crucial to the control of COVID-19, from self isolating and testing to vaccination uptake [1]. A key prevention behaviour in early stages of the pandemic was polymerase chain reaction (PCR) testing for . In 2020-21, COVID-19 prevention strategies were often reliant on people getting a PCR test. This could be required when community members had been in contact with a positive case, had COVID-19 symptoms (e.g. fever, cough, sore throat), needed to travel from an outbreak area to another region, and for certain professions (e.g. health workers). In Australia, community members were required to self-isolate at home until they returned a negative PCR test result, and this test-trace-isolate strategy was used to determine the need for short-term localised restrictions until linked clusters of cases were brought under control[3]. In early 2020 there was little research on COVID-19 testing behaviours given the very new nature of this issue, but media reports suggested different barriers existed across countries, which was confirmed in subsequent research. " METHODS 3a) Description of trial design (such as parallel, factorial) including allocation ratio Does your paper address CONSORT subitem 2b? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study "This program of work aimed to develop and test an intervention to address COVID-19 PCR testing barriers, to address the varying health literacy needs of the community. The intervention was developed and evaluated through 4 phases from June 2020 to November 2021.
• Phase 1, in June 2020, aimed to identify the range of barriers to COVID-19 testing. • Phase 2, in November 2020, aimed to estimate the prevalence of barriers to COVID-19 testing, to target interventions to the most important issues. • Phase 3, in February-March 2021, aimed to test the efficacy of providing health literacysensitive written information (i.e. adapted for people with lower health literacy) for all capability and motivation barriers identified in Phase 2, where individuals could view information to make a plan for their top 3 barriers to testing. • Phase 4, in November 2021, aimed to address design issues in Phase 3 and test the efficacy of providing health literacy-sensitive audio-visual interventions (simple animation or Tiktok style video) for a smaller selection of common barriers for people with lower health literacy, identified in Phase 2." 3b) Important changes to methods after trial commencement (such as eligibility criteria), with reasons Your answer must have a minimum of 25 characters.
Does your paper address CONSORT subitem 3a? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study "Study design Phase 1 and 2 both used a national survey study design. Phase 1 involved a survey of social media users using basic descriptive statistics. Phase 2 recruited a more representative sample via an online market research panel company with analysis comparing people with lower versus higher health literacy. Phase 3 and 4 used a randomised experiment design. Phase 3 used a 2 x 2 factorial design for COVID-19 testing intentions (2 groups compared post-intervention) and behavior (2 groups compared after 4 weeks), summarised in figure 1. Phase 4 used a 3 arm trial design for COVID-19 testing intentions (3 groups compared postintervention) and behavior after 4 weeks, summarised in figure 1." Does your paper address CONSORT subitem 3b? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study subitem not at all important 4a) Eligibility criteria for participants 3b-i) Bug fixes, Downtimes, Content Changes Bug �xes, Downtimes, Content Changes: ehealth systems are often dynamic systems. A description of changes to methods therefore also includes important changes made on the intervention or comparator during the trial (e.g., major bug �xes or changes in the functionality or content) (5-iii) and other "unexpected events" that may have in�uenced study design such as staff changes, system failures/downtimes, etc. [2].
Does your paper address subitem 3b-i?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study subitem not at all important 1 2 3 4 5 essential Does your paper address CONSORT subitem 4a? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study "This included any adults aged 18+, with quota sampling based on age, gender and education groups. In Phase 4, social media users aged 18-39 on Facebook and Instagram were targeted with ads and further participants were recruited via the online panel company, with quota sampling based on education. Different states in Australia were targeted at different times of recruitment, so that participants were only recruited when there were very few or no cases in their state (when a test-trace-isolate strategy can be effective for containing spread)."

4a-i) Computer / Internet literacy
Computer / Internet literacy is often an implicit "de facto" eligibility criterion -this should be explicitly clari�ed.
Does your paper address subitem 4a-i?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study subitem not at all important 1 2 3 4 5 essential 4a-ii) Open vs. closed, web-based vs. face-to-face assessments: Open vs. closed, web-based vs. face-to-face assessments: Mention how participants were recruited (online vs. o�ine), e.g., from an open access website or from a clinic, and clarify if this was a purely web-based trial, or there were face-to-face components (as part of the intervention or for assessment), i.e., to what degree got the study team to know the participant. In online-only trials, clarify if participants were quasi-anonymous and whether having multiple identities was possible or whether technical or logistical measures (e.g., cookies, email con�rmation, phone calls) were used to detect/prevent these.
Does your paper address subitem 4a-ii? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study "In Phase 1 social media users were asked to participate in a series of 10-minute surveys, with COVID-19 testing questions included in June 2020. Phase 2 recruited a nationally representative sample, where eligible panel members were invited to participate through the company's usual channels. A similar procedure was used for Phases 3 and 4 with recruitment through an online panel company All data were collected and stored in anonymous format, but participants could provide contact details to receive compensation via points for online panel members and prize draws for gift vouchers if recruited via social media." CONSORT-EHEALTH (V 1.6.1) -Submission/Publication Form https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_OimqcS...
subitem not at all important 1 2 3 4 5 essential 4b) Settings and locations where the data were collected 4a-iii) Information giving during recruitment Information given during recruitment. Specify how participants were briefed for recruitment and in the informed consent procedures (e.g., publish the informed consent documentation as appendix, see also item X26), as this information may have an effect on user self-selection, user expectation and may also bias results.

Does your paper address subitem 4a-iii?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study "After indicating their informed consent, participants completed a 10 minute online survey" CONSORT-EHEALTH (V 1.6.1) -Submission/Publication Form https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_OimqcS...
subitem not at all important 1 2 3 4 5 essential Does your paper address CONSORT subitem 4b? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study "In Phase 1 social media users were asked to participate in a series of 10-minute surveys, with COVID-19 testing questions included in June 2020. Phase 2 recruited a nationally representative sample, where eligible panel members were invited to participate through the company's usual channels. A similar procedure was used for Phases 3 and 4 with recruitment through an online panel company.
In Phase 4, social media users aged 18-39 on Facebook and Instagram were targeted with ads and further participants were recruited via the online panel company, with quota sampling based on education. Different states in Australia were targeted at different times of recruitment, so that participants were only recruited when there were very few or no cases in their state (when a test-trace-isolate strategy can be effective for containing spread)."

4b-i) Report if outcomes were (self-)assessed through online questionnaires
Clearly report if outcomes were (self-)assessed through online questionnaires (as common in web-based trials) or otherwise.
subitem not at all important 1 2 3 4 5 essential Does your paper address subitem 4b-i? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study "Survey questions for Phases 1 and 2 are provided in supplementary file 1. In each Phase we measured variables shown to be associated with differences in understanding of COVID-19 symptoms and prevention measures in our previous research [13], [18]: age, gender, language, health literacy, trust, living alone, prior COVID test. For the trials, our primary outcome was intention to undergo testing for COVID-19 if symptomatic (Table 3) (measured in a broad way for Phase 3, and a more specific way for Phase 4 to increase sensitivity).
Secondary outcomes included intentions about other prevention behaviours (self-isolation if symptomatic, social distancing 1.5 meters, washing hands regularly, wearing masks in crowded indoor areas), understanding of messaging, risk perceptions, social stigma, and self-efficacy (i.e. confidence in overcoming perceived barriers to testing). In Phase 3 only, self-reported prevention behaviour and intentions were assessed after 1 month, with our prior survey data suggesting >20% of participants would experience symptoms over that time. See Table 1."

4b-ii) Report how institutional affiliations are displayed
Report how institutional a�liations are displayed to potential participants [on ehealth media], as a�liations with prestigious hospitals or universities may affect volunteer rates, use, and reactions with regards to an intervention.(Not a required item -describe only if this may bias results) Your answer must have a minimum of 25 characters.

5)
The interventions for each group with sufficient details to allow replication, including how and when they were actually administered subitem not at all important 1 2 3 4 5 essential Does your paper address subitem 4b-ii?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study Not applicable

5-i) Mention names, credential, affiliations of the developers, sponsors, and owners
Mention names, credential, a�liations of the developers, sponsors, and owners [6] (if authors/evaluators are owners or developer of the software, this needs to be declared in a "Con�ict of interest" section or mentioned elsewhere in the manuscript).
subitem not at all important 1 2 3 4 5 essential Does your paper address subitem 5-i?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study "The aim of Phase 4 was to develop a more targeted communication intervention with further refined testing outcome measures. We selected 4 capability (knowledge) barriers from the most prevalent issues for people with lower health literacy in Phase 2 and developed two audio-visual intervention scripts to address these: a simple animation in the style of Australian government advertisements, and a Tiktok-style video developed from the same information by a pharmacist with a large online following for COVID-19 information videos.
We thank the participants of the longitudinal COVID-19 survey for their ongoing participation in this research, Wendy Liang for consumer input for the written intervention, and Mustafa Dhahir for developing the Tiktok version of the intervention. The surveys were not specifically funded, but in-kind support was provided by authors with research fellowships.

5-ii) Describe the history/development process
Describe the history/development process of the application and previous formative evaluations (e.g., focus groups, usability testing), as these will have an impact on adoption/use rates and help with interpreting results.
subitem not at all important 1 2 3 4 5 essential Does your paper address subitem 5-ii?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study The entire paper addresses this through 4 phases of understanding and addressing the barriers to COVID testing

5-iii) Revisions and updating
Revisions and updating. Clearly mention the date and/or version number of the application/intervention (and comparator, if applicable) evaluated, or describe whether the intervention underwent major changes during the evaluation process, or whether the development and/or content was "frozen" during the trial. Describe dynamic components such as news feeds or changing content which may have an impact on the replicability of the intervention (for unexpected events see item 3b).

Does your paper address subitem 5-iii?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study Not applicable; content is unchanged and provided in screenshots/transcripts/URL links

5-iv) Quality assurance methods
Provide information on quality assurance methods to ensure accuracy and quality of information provided [1], if applicable.
Does your paper address subitem 5-iv?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study Anonymous data is available from the authors.

5-v)
Ensure replicability by publishing the source code, and/or providing screenshots/screen-capture video, and/or providing flowcharts of the algorithms used Ensure replicability by publishing the source code, and/or providing screenshots/screencapture video, and/or providing �owcharts of the algorithms used. Replicability (i.e., other researchers should in principle be able to replicate the study) is a hallmark of scienti�c reporting.
subitem not at all important 1 2 3 4 5 essential Does your paper address subitem 5-v?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study Multimedia appendix provides URLs, transcripts and screenshots "Images and text for the Phase 4 intervention are provided in supplementary file 3. There were two audio-visual interventions: one was an animation and the other was a TikTok-style video, which was more humorous. Both covered the following barriers to COVID-19 testing, which were identified as the most prevalent knowledge issues for people with lower health literacy in

5-vi) Digital preservation
Digital preservation: Provide the URL of the application, but as the intervention is likely to change or disappear over the course of the years; also make sure the intervention is archived (Internet Archive, webcitation.org, and/or publishing the source code or screenshots/videos alongside the article). As pages behind login screens cannot be archived, consider creating demo pages which are accessible without login.
subitem not at all important 1 2 3 4 5 essential Does your paper address subitem 5-vi?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study Multimedia appendix provides URLs, transcripts and screenshots "Images and text for the Phase 4 intervention are provided in supplementary file 3. There were two audio-visual interventions: one was an animation and the other was a TikTok-style video, which was more humorous. Both covered the following barriers to COVID-19 testing, which were identified as the most prevalent knowledge issues for people with lower health literacy in

5-vii) Access
Access: Describe how participants accessed the application, in what setting/context, if they had to pay (or were paid) or not, whether they had to be a member of speci�c group. If known, describe how participants obtained "access to the platform and Internet" [1]. To ensure access for editors/reviewers/readers, consider to provide a "backdoor" login account or demo mode for reviewers/readers to explore the application (also important for archiving purposes, see vi).
subitem not at all important 1 2 3 4 5 essential Does your paper address subitem 5-vii? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study "Phase 1 and 2 both used a national survey study design. Phase 1 involved a survey of social media users using basic descriptive statistics. Phase 2 recruited a more representative sample via an online market research panel company with analysis comparing people with lower versus higher health literacy. Phase 3 and 4 used a randomised experiment design. Phase 3 used a 2 x 2 factorial design for COVID-19 testing intentions (2 groups compared post-intervention) and behavior (2 groups compared after 4 weeks), summarised in figure 1. Phase 4 used a 3 arm trial design for COVID-19 testing intentions (3 groups compared post-intervention) and behavior after 4 weeks, summarised in figure 1." Does your paper address subitem 5-viii? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study Images and text for the Phase 4 intervention are provided in supplementary file 3. There were two audio-visual interventions: one was an animation and the other was a TikTok-style video, which was more humorous. Both covered the following barriers to COVID-19 testing, which were identified as the most prevalent knowledge issues for people with lower health literacy in Phase 2:

5-viii) Mode of delivery, features/functionalities/components of the intervention and comparator, and the theoretical framework
• I know what symptoms I have and don't believe they are COVID-19 ones e.g. hayfever/normal cold CONSORT-EHEALTH (V 1.6.1) -Submission/Publication

5-ix) Describe use parameters
Describe use parameters (e.g., intended "doses" and optimal timing for use). Clarify what instructions or recommendations were given to the user, e.g., regarding timing, frequency, heaviness of use, if any, or was the intervention used ad libitum.
Does your paper address subitem 5-ix?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study "Those randomised to the intervention groups viewed a 2 minute audio-visual intervention, while those in the control group viewed standard written government information. Access to the outcome questions to complete the survey was enabled after 73 seconds for the animation and 65 seconds for the TikTok (the lengths of the audio-visual intervention) to increase the chance that participants viewed the intervention." CONSORT-EHEALTH (V 1.6.1) -Submission/Publication

5-x) Clarify the level of human involvement
Clarify the level of human involvement (care providers or health professionals, also technical assistance) in the e-intervention or as co-intervention (detail number and expertise of professionals involved, if any, as well as "type of assistance offered, the timing and frequency of the support, how it is initiated, and the medium by which the assistance is delivered". It may be necessary to distinguish between the level of human involvement required for the trial, and the level of human involvement required for a routine application outside of a RCT setting (discuss under item 21 -generalizability).

Does your paper address subitem 5-x?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study Not applicable -videos only

5-xi) Report any prompts/reminders used
Report any prompts/reminders used: Clarify if there were prompts (letters, emails, phone calls, SMS) to use the application, what triggered them, frequency etc. It may be necessary to distinguish between the level of prompts/reminders required for the trial, and the level of prompts/reminders for a routine application outside of a RCT setting (discuss under item 21 -generalizability).
Does your paper address subitem 5-xi? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study "In Phase 3, they were randomised to view written government information or the intervention, and completed outcome questions. Those randomised to the intervention selected three relevant barriers and viewed health literacy-sensitive information about those issues, and created a plan for one chosen barrier. They were asked to create an action plan to help them overcome their barriers, and received weekly reminders with a screenshot of their action plan by email. After 4 weeks, all participants received a 5 minute online survey (see Table 3).
In Phase 4, social media users aged 18-39 on Facebook and Instagram were targeted with ads and further participants were recruited via the online panel company, with quota sampling based on education. Different states in Australia were targeted at different times of recruitment, so that participants were only recruited when there were very few or no cases in their state (when a test-trace-isolate strategy can be effective for containing spread). The following advertisement text was used for social media: "We want to hear from you! Complete a short survey about COVID-19 and be in with the chance to win a $20 gift card." All participants answered a 10 minute survey (see Table 4). Those randomised to the intervention groups viewed a 2 minute audio-visual intervention, while those in the control group viewed standard written government information. Access to the outcome questions to complete the survey was enabled after 73 seconds for the animation and 65 seconds for the TikTok (the lengths of the audio-visual intervention) to increase the chance that participants viewed the intervention." CONSORT-EHEALTH (V 1.6.1) -Submission/Publication Form https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_OimqcS...
subitem not at all important 1 2 3 4 5 essential 6a) Completely defined pre-specified primary and secondary outcome measures, including how and when they were assessed 5-xii) Describe any co-interventions (incl. training/support) Describe any co-interventions (incl. training/support): Clearly state any interventions that are provided in addition to the targeted eHealth intervention, as ehealth intervention may not be designed as stand-alone intervention. This includes training sessions and support [1]. It may be necessary to distinguish between the level of training required for the trial, and the level of training for a routine application outside of a RCT setting (discuss under item 21 -generalizability.

Does your paper address subitem 5-xii? *
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study 6a-ii) Describe whether and how "use" (including intensity of use/dosage) was defined/measured/monitored Describe whether and how "use" (including intensity of use/dosage) was de�ned/measured/monitored (logins, log�le analysis, etc.). Use/adoption metrics are important process outcomes that should be reported in any ehealth trial.
Does your paper address subitem 6a-ii?

Copy and paste relevant sections from manuscript text
One off interventions; further use/access not evaluated 6a-iii) Describe whether, how, and when qualitative feedback from participants was obtained Describe whether, how, and when qualitative feedback from participants was obtained (e.g., through emails, feedback forms, interviews, focus groups).
6b) Any changes to trial outcomes after the trial commenced, with reasons 7a) How sample size was determined NPT: When applicable, details of whether and how the clustering by care provides or centers was addressed subitem not at all important 1 2 3 4 5 essential Does your paper address subitem 6a-iii?
Copy and paste relevant sections from manuscript text " Table 2

maps all the barriers identified in open survey responses to the COM-B drivers of behaviour (capability, opportunity and motivation)."
Does your paper address CONSORT subitem 6b? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study Not applicable, trial was pre-registered 7a-i) Describe whether and how expected attrition was taken into account when calculating the sample size Describe whether and how expected attrition was taken into account when calculating the sample size.
7b) When applicable, explanation of any interim analyses and stopping guidelines 8a) Method used to generate the random allocation sequence NPT: When applicable, how care providers were allocated to each trial group Does your paper address subitem 7a-i?
Copy and paste relevant sections from manuscript title (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study Does your paper address CONSORT subitem 7b? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study 8b) Type of randomisation; details of any restriction (such as blocking and block size) Does your paper address CONSORT subitem 8a? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study "A similar procedure was used for Phases 3 and 4 with recruitment through an online panel company, but participants were randomised to view different versions of COVID-19 testing information. In Phase 3, they were randomised to view written government information or the intervention, and completed outcome questions. Those randomised to the intervention selected three relevant barriers and viewed health literacy-sensitive information about those issues, and created a plan for one chosen barrier. They were asked to create an action plan to help them overcome their barriers, and received weekly reminders with a screenshot of their action plan by email. After 4 weeks, all participants received a 5 minute online survey (see Table 3).
In Phase 4, social media users aged 18-39 on Facebook and Instagram were targeted with ads and further participants were recruited via the online panel company, with quota sampling based on education. Different states in Australia were targeted at different times of recruitment, so that participants were only recruited when there were very few or no cases in their state (when a test-trace-isolate strategy can be effective for containing spread). The following advertisement text was used for social media: "We want to hear from you! Complete a short survey about COVID-19 and be in with the chance to win a $20 gift card." All participants answered a 10 minute survey (see Table 4). Those randomised to the intervention groups viewed a 2 minute audio-visual intervention, while those in the control group viewed standard written government information. " Does your paper address CONSORT subitem 8b? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study Not applicable -no restriction; equal groups CONSORT-EHEALTH (V 1.6.1) -Submission/Publication Form https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_OimqcS... 9) Mechanism used to implement the random allocation sequence (such as sequentially numbered containers), describing any steps taken to conceal the sequence until interventions were assigned 10) Who generated the random allocation sequence, who enrolled participants, and who assigned participants to interventions 11a) If done, who was blinded after assignment to interventions (for example, participants, care providers, those assessing outcomes) and how NPT: Whether or not administering co-interventions were blinded to group assignment Does your paper address CONSORT subitem 9? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study Not applicable -randomization done within survey itself Does your paper address CONSORT subitem 10? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study subitem not at all important 1 2 3 4 5 essential subitem not at all important 1 2 3 4 5 essential 11a-i) Specify who was blinded, and who wasn't Specify who was blinded, and who wasn't. Usually, in web-based trials it is not possible to blind the participants [1, 3] (this should be clearly acknowledged), but it may be possible to blind outcome assessors, those doing data analysis or those administering cointerventions (if any).

Does your paper address subitem 11a-i? *
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study Not applicable -Blinding not possible for interactive interventions online 11a-ii) Discuss e.g., whether participants knew which intervention was the "intervention of interest" and which one was the "comparator" Informed consent procedures (4a-ii) can create biases and certain expectations -discuss e.g., whether participants knew which intervention was the "intervention of interest" and which one was the "comparator".

11b) If relevant, description of the similarity of interventions
(this item is usually not relevant for ehealth trials as it refers to similarity of a placebo or sham intervention to a active medication/intervention) 12a) Statistical methods used to compare groups for primary and secondary outcomes NPT: When applicable, details of whether and how the clustering by care providers or centers was addressed Does your paper address subitem 11a-ii?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study Not applicable -Blinding not possible for interactive interventions online Does your paper address CONSORT subitem 11b? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study subitem not at all important 1 2 3 4 5 essential Does your paper address CONSORT subitem 12a? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study "Analyses For Phases 1 and 2, participant characteristics and survey question responses are reported descriptively, using a content analysis approach for open responses and χ^2 tests to compare responses across health literacy levels. Two researchers mapped the text from open responses to components of the COM-B model, with discussion to resolve discrepancies. For Phases 3 and 4, analyses were conducted using planned contrasts between the intervention arms and control arm, implemented in regression models. Continuous outcomes were analysed using linear regression to estimate marginal mean differences; dichotomous outcomes were analysed using generalized linear models with a modified Poisson approach (log link, robust standard errors) to estimate relative risks; count variables were analysed using Poisson regression to estimate relative risks. In Phase 3, analyses controlled for age, gender, language, health literacy, trust, living alone, and previous COVID-19 testing. In Phase 4, positive baseline intention, age, gender, language, health literacy, trust, and perceived COVID-19 risk in Australia were controlled for. Interactions between health literacy and randomised condition were also explored." 12a-i) Imputation techniques to deal with attrition / missing values Imputation techniques to deal with attrition / missing values: Not all participants will use the intervention/comparator as intended and attrition is typically high in ehealth trials. Specify how participants who did not use the application or dropped out from the trial were treated in the statistical analysis (a complete case analysis is strongly discouraged, and simple imputation techniques such as LOCF may also be problematic [4]). Does your paper address subitem 12a-i? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study Not applicable -no imputation Does your paper address CONSORT subitem 12b? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study "Interactions between health literacy and randomised condition were also explored."
subitem not at all important 1 2 3 4 5 essential Does your paper address subitem X26-i?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study

x26-ii) Outline informed consent procedures
Outline informed consent procedures e.g., if consent was obtained o�ine or online (how? Checkbox, etc.?), and what information was provided (see 4a-ii). See [6] for some items to be included in informed consent documents.

Does your paper address subitem X26-ii?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study "All data were collected and stored in anonymous format,...After indicating their informed consent, participants completed a 10 minute online survey" CONSORT-EHEALTH (V 1.6.1) -Submission/Publication Form https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_OimqcS...
subitem not at all important 1 2 3 4 5 essential RESULTS 13a) For each group, the numbers of participants who were randomly assigned, received intended treatment, and were analysed for the primary outcome NPT: The number of care providers or centers performing the intervention in each group and the number of patients treated by each care provider in each center

X26-iii) Safety and security procedures
Safety and security procedures, incl. privacy considerations, and any steps taken to reduce the likelihood or detection of harm (e.g., education and training, availability of a hotline)

Does your paper address subitem X26-iii?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study "All data were collected and stored in anonymous format" CONSORT-EHEALTH (V 1.6.1) -Submission/Publication Form https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_OimqcS...

13b) For each group, losses and exclusions after randomisation, together with reasons
Does your paper address CONSORT subitem 13a? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study Does your paper address CONSORT subitem 13b? (NOTE: Preferably, this is shown in a CONSORT flow diagram) * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study subitem not at all important 1 2 3 4 5 essential 14a) Dates defining the periods of recruitment and follow-up

13b-i) Attrition diagram
Strongly recommended: An attrition diagram (e.g., proportion of participants still logging in or using the intervention/comparator in each group plotted over time, similar to a survival curve) or other �gures or tables demonstrating usage/dose/engagement.

Does your paper address subitem 13b-i?
Copy and paste relevant sections from the manuscript or cite the �gure number if applicable (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study subitem not at all important 1 2 3 4 5 essential Does your paper address CONSORT subitem 14a? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study 14a-i) Indicate if critical "secular events" fell into the study period Indicate if critical "secular events" fell into the study period, e.g., signi�cant changes in Internet resources available or "changes in computer hardware or Internet delivery resources" Does your paper address subitem 14a-i?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study 14b) Why the trial ended or was stopped (early) 15) A essential 16-i) Report multiple "denominators" and provide definitions Report multiple "denominators" and provide de�nitions: Report N's (and effect sizes) "across a range of study participation [and use] thresholds" [1], e.g., N exposed, N consented, N used more than x times, N used more than y weeks, N participants "used" the intervention/comparator at speci�c pre-de�ned time points of interest (in absolute and relative numbers per group). Always clearly de�ne "use" of the intervention.
Does your paper address subitem 16-i? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study Not applicable -one off intervention; but denominator for each phase is clearly defined throughout results tables

16-ii) Primary analysis should be intent-to-treat
Primary analysis should be intent-to-treat, secondary analyses could include comparing only "users", with the appropriate caveats that this is no longer a randomized sample (see 18-i).
17a) For each primary and secondary outcome, results for each group, and the estimated effect size and its precision (such as 95% confidence interval) subitem not at all important 1 2 3 4 5 essential Does your paper address subitem 16-ii?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study Does your paper address CONSORT subitem 17a? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study See results tables and appendices 17a-i) Presentation of process outcomes such as metrics of use and intensity of use In addition to primary/secondary (clinical) outcomes, the presentation of process outcomes such as metrics of use and intensity of use (dose, exposure) and their operational de�nitions is critical. This does not only refer to metrics of attrition (13-b) (often a binary variable), but also to more continuous exposure metrics such as "average session length". These must be accompanied by a technical description how a metric like a "session" is de�ned (e.g., timeout after idle time) [1] (report under item 6a).
17b) For binary outcomes, presentation of both absolute and relative effect sizes is recommended 18) Results of any other analyses performed, including subgroup analyses and adjusted analyses, distinguishing pre-specified from exploratory Does your paper address subitem 17a-i?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study Not applicable -one off intervention Does your paper address CONSORT subitem 17b? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study

18-i) Subgroup analysis of comparing only users
A subgroup analysis of comparing only users is not uncommon in ehealth trials, but if done, it must be stressed that this is a self-selected sample and no longer an unbiased sample from a randomized trial (see 16-iii).

Does your paper address subitem 18-i?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study Limitations identified by researchers are discussed and qualitative responses from participants included; no space for additional reflections as 4 phases covered 22-i) Restate study questions and summarize the answers suggested by the data, starting with primary outcomes and process outcomes (use) Restate study questions and summarize the answers suggested by the data, starting with primary outcomes and process outcomes (use).
subitem not at all important 1 2 3 4 5 essential Does your paper address subitem 22-i? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study "Principal results These results provide new insights into identifying and addressing behavioural barriers to COVID-19 testing, which is central to understanding and controlling COVID-19 and future pandemics. Phase 1 identified a wide range of barriers to COVID-19 testing that had not previously been described in the COVID-19 literature. These covered all three behavioural drivers in the COM-B model. Phase 2 found that the motivation and capability barriers were far more prevalent than opportunity barriers in Australia at the time of the study. Many barriers were reported as more prevalent amongst people with lower health literacy. Phases 3 and 4 tested different ways to address capability and motivation barriers. Phase 3 found no differences between standard government text about COVID-19 testing and a tailored text intervention that addressed many different barriers using health literacy design principles. Phase 4 found that audio-visual interventions to address key knowledge barriers are more effective than written government information for improving knowledge, but this was not enough to shift COVID-19 testing intentions in adjusted analyses. "

22-ii) Highlight unanswered new questions, suggest future research
Highlight unanswered new questions, suggest future research.

20-i) Typical limitations in ehealth trials
Typical limitations in ehealth trials: Participants in ehealth trials are rarely blinded. Ehealth trials often look at a multiplicity of outcomes, increasing risk for a Type I error. Discuss biases due to non-use of the intervention/usability issues, biases through informed consent procedures, unexpected events.
Does your paper address subitem 20-i? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study "Strengths and limitations This research began as an unfunded and rapidly developed response to the COVID-19 pandemic. By addressing methodological issues and building on the findings in each Phase, we were able to better target the final intervention and show the value of audio-visual formats to address common knowledge barriers among people with varying health literacy needs. Phase 1 identified the range of barriers to COVID-19 testing in Australia for the first time, but prevalence of the most important barriers could not be ascertained from these findings due to the reliance on open responses and a non-representative sample. The next phase aimed to address these methodological issues. Phase 2 identified the prevalence of COVID-19 testing barriers in a nationally representative sample, and highlighted important health literacy disparities. However, even the second phase was not representative of all community groups, particularly those from culturally and linguistically diverse backgrounds which has been identified as a key area of need in Australia and worldwide. We have conducted a separate survey with these groups using interpreters to conduct the survey in Phase 1 in preferred languages, as a partnership with Western Sydney Local health District[52]-[54].
In Phase 3, the intervention's highly tailored design meant that there was considerable heterogeneity in the intervention elements that participants received. This may have contributed to the lack of observed effect. It is possible there were ceiling effects for testing intentions when participants assumed they would get tested when they were not currently or recently thinking about the logistics of getting tested. It is also possible that participants did not engage with the text-based intervention content. We attempted to address these methodological issues in the final Phase 4 by focusing on a consistent set of key knowledge barriers in a more targeted group with lower baseline testing intentions (younger, lower education), using a more engaging intervention format (animation with text and audio, and a social media style video), and including more sensitive measures of testing intention to avoid potential biases.
The audio-visual interventions produced for Phase 4 have information that is specific to the Australian context so may not be useful in other countries, but can be used as a starting point for new knowledge interventions. We found that a simple and relatively cheap animation focused on key messages or a Tiktok style video that incorporated humour were both effective for increasing knowledge but not testing intentions. However, the findings may not be generalisable to other contexts, particularly where opportunity issues such as cost or physical access to testing is a problem. We expect there will be additional barriers to rapid antigen tests. Nevertheless, this paper provides a comprehensive list of testing barriers that may help us better prepare for future variants or the next pandemic. " 21) Generalisability (external validity, applicability) of the trial findings NPT: External validity of the trial �ndings according to the intervention, comparators, patients, and care providers or centers involved in the trial subitem not at all important 1 2 3 4 5 essential

21-i) Generalizability to other populations
Generalizability to other populations: In particular, discuss generalizability to a general Internet population, outside of a RCT setting, and general patient population, including applicability of the study results for other organizations Does your paper address subitem 21-i?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study "The audio-visual interventions produced for Phase 4 have information that is specific to the Australian context so may not be useful in other countries, but can be used as a starting point for new knowledge interventions. We found that a simple and relatively cheap animation focused on key messages or a Tiktok style video that incorporated humour were both effective for increasing knowledge but not testing intentions. However, the findings may not be generalisable to other contexts, particularly where opportunity issues such as cost or physical access to testing is a problem. We expect there will be additional barriers to rapid antigen tests. Nevertheless, this paper provides a comprehensive list of testing barriers that may help us better prepare for future variants or the next pandemic. " CONSORT-EHEALTH (V 1.6.1) -Submission/Publication Form https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_OimqcS...

X27) Conflicts of Interest (not a CONSORT item)
subitem not at all important 1 2 3 4 5 essential Does your paper address CONSORT subitem 25? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or brie�y explain why the item is not applicable/relevant for your study "The surveys were not specifically funded, but in-kind support was provided by authors with research fellowships. X27-i) State the relation of the study team towards the system being evaluated In addition to the usual declaration of interests (�nancial or otherwise), also state the relation of the study team towards the system being evaluated, i.e., state if the authors/evaluators are distinct from or identical with the developers/sponsors of the intervention.

yes no
Other:

yes no
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