Evaluation of a multinational, multilingual vaccine debate on Twitter

Highlights

• Twitter messages can indirectly reflect public opinion about vaccine issues or events.

• Most messages were created by private persons.

• The debate focuses on local and current events.

Abstract

Background

Public confidence in an immunization programme is a pivotal determinant of the programme’s success. The mining of social media is increasingly employed to provide insight into the public’s sentiment. This research further explores the value of monitoring social media to understand public sentiment about an international vaccination programme.

Objective

To gain insight into international public discussion on the paediatric pentavalent vaccine (DTP-HepB-Hib) programme by analysing Twitter messages.

Methods

Using a multilingual search, we retrospectively collected all public Twitter messages mentioning the DTP-HepB-Hib vaccine from July 2006 until May 2015. We analysed message characteristics by frequency of referencing other websites, type of websites, and geographic focus of the discussion. In addition, a sample of messages was manually annotated for positive or negative message tone.

Results

We retrieved 5771 messages. Only 3.1% of the messages were reactions to other messages, and 86.6% referred to websites, mostly news sites (70.7%), other social media (9.8%), and health-information sites (9.5%). Country mentions were identified in 70.4% of the messages, of which India (35.4%), Indonesia (18.3%), and Vietnam (13.9%) were the most prevalent. In the annotated sample, 63% of the messages showed a positive or neutral sentiment about DTP-HepB-Hib. Peaks in negative and positive messages could be related to country-specific programme events.

Conclusions

Public messages about DTP-HepB-Hib were characterized by little interaction between tweeters, and by frequent referencing of websites and other information links. Twitter messages can indirectly reflect the public’s opinion about major events in the debates about the DTP-HepB-Hib vaccine.

Introduction

Vaccination programmes are among the most effective means for improving population health. Particularly at the time of programme introduction, they tend to be accompanied by public discussion [1], [2]. This may increase public awareness of the vaccine and affect the programme beneficially [3]. However, public concern may lead to reduced uptake or even jeopardize the entire immunization programme [4], [5]. Therefore, detecting changes in public sentiment early is important to understand its origin and dynamics and to inform appropriate measures to investigate concerns, guide public health decision-making, or help identify issues with the vaccine or the vaccination programme.

Public attention and sentiment about vaccines have been evaluated previously by analysing different types of social-media messages and user-generated web content. Messages from the social-media platform MySpace were used for monitoring public sentiment about the human papillomavirus (HPV) vaccine [6]. Public news items about the HPV vaccine were shown to influence the public’s awareness and opinion about HPV infection and vaccine in the United States [7]. Sentiments about an influenza vaccine shared through Twitter messages were found to correlate highly with US vaccination rates as reported by the Centers for Disease Control and Prevention [8]. International debates about vaccines and the course and drivers of public confidence have also been studied through analysis of media sources such as news sites, blogs, and governmental reports [2], [9]. Twitter and other social media have frequently been used for post-marketing surveillance of pharmaceutical safety issues [10], [11], [12]. Some studies have concluded that monitoring social media is more suitable for measuring public awareness of known safety issues than for providing clues about new safety signals [13].

Since 2001, a pentavalent paediatric vaccine against diphtheria, tetanus, pertussis, hepatitis B and Haemophilus influenzae type b (DTP-HepB-Hib) has been introduced into more than 70 low- and middle-income countries (LMICs) [14]. In a number of countries, the introduction of the vaccine was accompanied by a critical debate following a suspected association with the death of children, none of which have been deemed as causally related to the vaccine [15]. In India, a petition and a lawsuit was filed against the vaccine [16], [17]. In Sri Lanka, Bhutan, and Vietnam, the market authorization for the vaccine was even temporarily suspended [18].

In this study, we explore the value of public Twitter messages to gain insight into the multinational debate on the pentavalent vaccine.