The Impact of COVID-19 Pandemic Social Distancing and Mask Mandates on the Prevalence of Influenza and RSV During Their Peak Season

Background: Influenza and bronchiolitis are serious infections especially among vulnerable pediatric populations. Earlier studies have suggested that the transmission of influenza viruses can be reduced by face masking and social distancing measures. In response to the COVID-19 pandemic, Ohio adopted various measures including school closing, travel restrictions, social distancing, and face masking in March, 2020. These measures have created a unique opportunity to study the impact of social distancing measures on the spread of potentially serious viral infections such as influenza and respiratory syncytial viral (RSV) infections of children in our locality.

Methods: This is a retrospective cohort study conducted at Akron Children’s hospital in Northeast Ohio where the peak respiratory season extends from October to April. The primary outcome was to evaluate the prevalence of influenza A and B and RSV infections before and after implementation of social distancing measures. Prevalence of SARS-CoV-2 was also tracked for comparison. Viral assay data were collected between October 1, 2020 through April 30th, 2021 (during the pandemic and social distancing implementation) and compared with two pre-COVID-19 respiratory seasons: 2018-19 and 2019-20. Results from all patients who received viral testing as a part of their medical care were included. Viral tests included rapid antigen tests for Influenza A/B and RSV (Quidel SoFIA), Respiratory Film Array (BioFire, includes flu, RSV, and SARS-CoV-2 targets), and single target tests for SARS-CoV-2 from multiple vendors (see Table 1).

Results: There was a dramatic increase in viral testing in the 2020-2021 respiratory season. With most of the new test targeting SARS-CoV-2, Flu and RSV antigen tests decreased significantly but were replaced in part by Respiratory FilmArray use (Table 1). Pre-COVID-19, the peak incidence of RSV occurred in December for the 2018-19 (28.9%, average of 8.8%) and 2019-20 (24.7%, average of 8.8%) seasons. After social distancing measures, the incidence and positivity rate for RSV was 0% until March 14, 2021 when the first RSV case was detected in our locality, concurrent with relaxation of social distancing measures. Pre-COVID 19, the peak incidence of Influenza A virus occurred during February in the seasons 2018-19 (40.9 %; average of 13.6%) and 2019-20 (24.1%, average of 6.1%). Influenza B had a low incidence throughout 2018-2019 (average of 0.3%) with a peak during January in the 2019-2020 season (24.0%, average of 6.8%). During the 2020-2021 season, we detected only two isolated cases of Influenza B virus and no cases of Influenza A virus through April 30, 2021 (Figure-1).

Conclusion: Social distancing and mask mandates can be effective tools to decrease the rates of potentially serious infections such as Influenza and RSV in the pediatric population. Travel restrictions and school closures likely had an affect but were not evaluated during this study.