Before 2020, annual respiratory syncytial virus (RSV) epidemics tended to begin in October, peak in December, and end by April. But patterns changed after the pandemic began, according to US Centers for Disease Control and Prevention data collected between 2017 and 2023. No typical winter RSV epidemic occurred during 2020-2021. But the atypical 2021-2022 epidemic began in May and lasted until January, perhaps because of fewer school closures and less masking.
Source: JAMA Online First