Collateral Benefit of COVID-19 Control Measures on Influenza Activity, Taiwan

Taiwan has strictly followed infection control measures to prevent spread of coronavirus disease. Meanwhile, nationwide surveillance data revealed drastic decreases in influenza diagnoses in outpatient departments, positivity rates of clinical specimens, and confirmed severe cases during the first 12 weeks of 2020 compared with the same period of 2019.

Between the start of the SARS-CoV-2 outbreak in Reggio Emilia at the end of February and March 24, the province has had 460 hospitalizations in all hospitals. Among these, 2 (0.4%) patients (1,2) had acute ischemic events involving abdominal viscera; therefore, these events should not be considered too rare. Visceral infarction is probably a clinical manifestation of the prothrombotic state that has been described in patients with COVID-19 (1)(2)(3)(4)(5)(6). Consistently, reports about pathological changes in organs other than the lungs describe parenchymal cells necrosis and small-vessel thrombosis (7).
The possibility of abdominal visceral infarction during COVID-19 has major implications in clinical practice. First, when patients with COVID-19 report severe abdominal pain, visceral infarction should be considered in differential diagnosis and taken into account in laboratory and imaging diagnostic workups. Second, this finding should further prompt the scientific community to stress the need to routinely use LMWH in patients with COVID-19 and to open the debate on the appropriate dosage. Finally, the prothrombotic state in patients with COVID-19 may justify therapeutic rather than prophylactic LMWH.

Collateral Benefit of COVID-19 Control Measures on Influenza Activity, Taiwan
Shu-Chen Kuo, Shu-Man Shih, Li-Hsin Chien, Chao A. Hsiung has adhered well to control measures that included avoiding gatherings, maintaining social distance, mask wearing, hand and respiratory hygiene, temperature monitoring, and quarantine of high-risk and sick persons ( Figure 1, panel A). Although the success of these measures for limiting COVID-19 transmission remains to be determined, nationwide surveillance has shown the rapid decline of influenza activity during the first 12 weeks of 2020 (through March 21) in Taiwan.
The Taiwan National Infectious Disease Statistics System (2), maintained by the Taiwan Centers for Disease Control, is an open data portal that provides nationwide surveillance data on infectious diseases (https://nidss.cdc.gov.tw). For this study, we analyzed data from outpatient department visits for selected syndromes, clinical specimen testing, isolated respiratory pathogens, and confirmed severe cases (Appendix, https://wwwnc.cdc.gov/EID/article/26/8/20-1192-App1.pdf). The institutional review board of the National Health Research Institutes approved this study (EC1051207-R4).
We compared changes across the first 12 weeks of 2020 with data from the same period of 2019 using simple linear regression. (The 9-day Lunar New Year holiday in week 6 of 2019, when most healthcare service was unavailable, resulted in extreme data; therefore, we excluded these data from analysis.) We saw fewer outpatient department visits for influenza-like illness (ILI) and ILI diagnoses per 1,000 visits during weeks 8-12 of 2020 compared with 2019 ( Figure,   for positive samples (-360 vs. -77 per week; p<0.05) also differed between 2020 and 2019 ( Figure 1, panel B). Both the number of influenza strains isolated from clinical specimens in commissioned laboratories and the positivity rate dropped drastically in 2020; the trends were different from 2019 (p<0.05 for both) (Figure 1, panel C).
The number of cases of confirmed influenza with severe complications decreased from 99 to 1 in 2020, compared with a decrease from 44 to 22 in 2019 (p<0.05) ( Figure  1, panel D). In contrast, the number of outpatient department visits for varicella and the number of varicella diagnoses per 1,000 visits remained similar in 2020 and 2019 (p = 0.660 for outpatient department visits and p = 0.157 for varicella diagnosis) (Figure 1, panel E).
The functional healthcare and surveillance systems in Taiwan, the government's efforts to identify causes of ILI during the COVID-19 pandemic, and sufficient laboratory capacity ensure appropriate influenza testing and reporting of results. Healthcare avoidance during COVID-19 pandemic may be an important confounder for the results we reported. However, because of awareness of the similarities in symptoms between COVID-19 and influenza and the low number of CO-VID-19 patients in Taiwan (<200 cases as of March 21, 2020), patients with ILI would not avoid seeking medical help for a diagnosis. Healthcare avoidance also did not explain the lower number of severe influenza cases observed in 2020 (Figure 1, panel D). Therefore, we believe that the decreasing influenza activity in Taiwan in 2020 is the result of strict control measures that were established in response to COVID-19. S evere acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the cause of the coronavirus disease (COVID-19) pandemic, is highly contagious and can put families of healthcare professionals at risk for both symptomatic COVID-19 and asymptomatic We found that all 5 asymptomatic household contacts of a Wuhan, China, physician with coronavirus disease had severe acute respiratory syndrome coronavirus 2 detected by PCR. The index patient and 2 contacts also had abnormal chest computed tomography scans. Asymptomatic infected household contacts of healthcare workers with coronavirus disease might be underrecognized.