Lead Director - Epidemiology CVS Health Elkins Park, United States
Background: Respiratory syncytial virus (RSV) and influenza viruses, and the secondary pneumonia they can cause, represent a large public health burden. These infections generate millions of healthcare visits and lead to tens of thousands of deaths in children and older adults in the United States (U.S.) each year. Recently, the seasonality, quantity, and severity of RSV-, pneumonia-, and influenza-related healthcare utilization may have been affected by the COVID-19 pandemic.
Objectives: To describe monthly trends in healthcare utilization attributable to RSV, influenza, pneumonia infections from January 2020 to December 2022 among children and older adults.
Methods: Two cohorts of interest were identified among research-eligible enrollees of a large U.S. commercial health plan: children ≤5 years old and adults ≥65 years old with healthcare visits and diagnoses of RSV, influenza, or pneumonia in any position. Rates of patients diagnosed and visits per eligible patients were calculated by age group, and calendar month, compared statistically using Mann-Kendall tests .
Results: In total, there were 967 visits for RSV, 23,596 for influenza, and 17,444 for pneumonia respectively among children; 6,635 visits for RSV, 135,859 for influenza, and 2,855,830 for pneumonia respectively among adults during the study period. Among young children, the largest monthly increase from the prior month in the diagnosis rate was seen in July 2021 (163%) and in October 2022 (209%) for RSV, in December 2021 (272%) and October 2022 (296%) for influenza, and December 2021 (78%) and December 2022 (77%) for pneumonia. Among older adults, the rate of RSV-related visits peaked in the last 3 months of 2021 and 2022 (max. 32 visits per 100,000); however, the monthly percent increase in patients diagnosed with RSV was highest in October 2022 (207%). Pneumonia-related healthcare utilization among older adults consistently peaked in the months of December.
Conclusions: An unexpected overlap was observed in the peaks of RSV and influenza in late 2022 in the pediatric group compared to historical trends. RSV infections have historically peaked in the December – February months. While a seasonal shift was also present among the elderly, the magnitude of change was less pronounced. Primary prevention tools such as vaccination is not currently available for RSV, therefore the burden and seasonality will likely continue to be influenced by other public health stressors
