Changes in hospital admissions associated with pediatric respiratory syncytial virus after the COVID-19 pandemic in Canada: an active surveillance study

Background: The COVID-19 pandemic affected the epidemiology of respiratory syncytial virus (RSV). We sought to describe tertiary care hospital admissions associated with pediatric RSV in 2022/23 in Canada and to assess pandemic-related changes. Methods: We conducted active surveillance of hospital-admitted infants and children aged 0 to 16 years at 13 Immunization Monitoring Program, Active (IMPACT) centres. We compared RSV-associated hospital admissions in 2022/23 with those in the prepandemic period (2017/18 through 2019/20). We calculated province-specific and age-stratified proportions of all-cause hospital admissions with RSV detection and age-stratified proportions of RSV-associated intensive care unit (ICU) admissions. We performed seasonal autoregressive integrated moving average (SARIMA) time-series analyses. Results: In 2022/23, 5362 RSV-associated hospital admissions occurred, including 1260 (23.5%) ICU admissions, both more than double the prepandemic yearly averages. Overall, the median age increased from 6 (interquartile range IQR 1 to 20) months to 9 (IQR 2 to 27) months (p Interpretation: In 2022/23, the number of RSV-associated hospital admissions and ICU admissions increased dramatically in Canadian pediatric hospitals. The greatest burden remained in infants younger than 6 months. Strategies for RSV immunization for young infants may have a substantial public health impact.