D3.133 - Association between Asthma and Risk of Respiratory Syncytial Virus-Acute Respiratory Infection in Adults 50 Years or Older Before and After the Covid 19-Pandemic in a Midwest Region of the U.S

The COVID-19 pandemic impacted the epidemiology (magnitude and circulation pattern) of non-COVID-19 infections like respiratory syncytial virus (RSV)-acute respiratory infection (ARI) in part due to behavioral and potentially immune shifts unique to the pandemic environment. This study aimed to assess the association between asthma and RSV-ARI in pre- and post-COVID-19 periods.

This is a matched case-control study based on the data collected in a 4-RSV Season prospective cohort study among adults 50 years and older in the U.S. The study was extended to assess the influence of the COVID-19 pandemic on the incidence of RSV, so the study analysis included 1,682 reconsented participants (out of 2,325 original participants for Seasons 1 and 2) and 829 newly recruited for Seasons 3 and 4. The analysis focused on comparing results between Season 1 (2019-2020; pre-pandemic) and Season 4 (2022-2023; post-pandemic) during each RSV season (Oct-Apr). Each PCR-confirmed RSV case (regardless of medically attended or not) was matched by age and sex to 2 controls without ARI within ±2 weeks of the date of RSV cases. A logistic regression model was performed to examine the extent to which prevalent asthma at the time of enrollment was associated with RSV-ARI before and after the COVID-19 pandemic. 

58 RSV cases and 116 matched controls for Season 1 and 39 RSV cases and 75 matched controls for Season 4 were identified (Table 1). Prevalence of asthma was similar between RSV cases and controls in Season 1 (10.3% [6/58] vs. 12.9% [15/116]), but was significantly higher among RSV cases compared to matched controls in Season 4 (23.1% [9/39] vs.5.3% [4/75]) (odds ratio (95% CI; p-value): 0.78 (0.28, 2.14; p=0.62) for Season 1 vs. 5.32 (1.49-19.03; p=0.011) for Season 4). 

The study highlights a significant increase in the association between asthma and the risk of RSV-ARI post-COVID-19 compared to pre-pandemic levels. This observed finding warrants further exploration of asthma's role in RSV susceptibility and outcomes in the evolving epidemiological landscape.