Respiratory Syncytial Virus, Influenza, and Coronavirus Disease 2019 Hospitalizations in Children in Colorado During the 2021-2022 Respiratory Virus Season

Objective To compare demographic characteristics, clinical features, and outcomes of children hospitalized with respiratory syncytial virus (RSV), influenza, or severe acute respiratory syndrome coronavirus 2 during their cocirculation 2021-2022 respiratory virus season. Methods We conducted a retrospective cohort study using Colorado's hospital respiratory surveillance data comparing coronavirus disease 2019 (COVID-19)-, influenza-, and RSV-hospitalized cases < 18 years of age admitted and undergoing standardized molecular testing between October 1, 2021, and April 30, 2022. Multivariable log-binomial regression modeling evaluated associations between pathogen type and diagnosis, intensive care unit admission, hospital length of stay, and highest level of respiratory support received. Results Among 847 hospitalized cases, 490 (57.9%) were RSV associated, 306 (36.1%) were COVID-19 associated, and 51 (6%) were influenza associated. Most RSV cases were <4 years of age (92.9%), whereas influenza hospitalizations were observed in older children. RSV cases were more likely to require oxygen support higher than nasal cannula compared with COVID-19 and influenza cases (P < .0001), although COVID-19 cases were more likely to require invasive mechanical ventilation than influenza and RSV cases (P < .0001). Using multivariable log-binomial regression analyses, compared with children with COVID-19, the risk of intensive care unit admission was highest among children with influenza (relative risk, 1.97; 95% CI, 1.22-3.19), whereas the risk of pneumonia, bronchiolitis, longer hospital length of stay, and need for oxygen were more likely among children with RSV. Conclusions In a season with respiratory pathogen cocirculation, children were hospitalized most commonly for RSV, were younger, and required higher oxygen support and non-invasive ventilation compared with children with influenza and COVID-19.