Respiratory Syncytial Virus Seasonality and Disease Severity among Children Under 5 in Atlanta, Georgia, United States, 2018–2023

Abstract Background The COVID-19 pandemic had dramatic impacts on the epidemiology of respiratory syncytial virus (RSV), a disease of importance in children under 5 years old. We used surveillance data collected by the Georgia Emerging Infections Program (GA EIP) to investigate seasonality and severity of RSV pre- versus post-pandemic in children under 5 years old in and near Atlanta, Georgia. Methods We analyzed 3,282 RSV-associated hospitalizations of children under 5 years old residing in the Atlanta area from 2018 to 2023. Hospitalizations were grouped into four distinct waves of RSV activity, two pre-pandemic and two post-pandemic. Using regression modeling, we assessed the impact of wave on length of hospital stay and intensive care unit (ICU) admission among all hospitalizations, and on length of ICU stay and mechanical ventilation among ICU admissions. Results The two post-pandemic waves of RSV-associated hospitalizations fell outside of the typical viral respiratory season (October – April) in the northern hemisphere, seemingly delayed by COVID-19 associated disruptions in transmission. Age at hospitalization and race/ethnicity differed significantly across all waves, with age increasing over time. Regression models for all hospitalizations showed a statistically significant reduction in severity (shorter length of hospital stay and lower risk of ICU admission) post-pandemic after adjustment for age and race/ethnicity. Analysis of ICU admissions adjusted for age, race/ethnicity, and underlying medical conditions tended towards shorter ICU stays and lower risk of mechanical ventilation post-pandemic, although these findings did not show statistical significance. Conclusions The COVID-19 pandemic delayed the expected annual seasonality of RSV in children under 5, and the delayed peaks of hospitalizations consisted of, on average, less severe disease than pre-pandemic.