Respiratory syncytial virus epidemic during the COVID‐19 pandemic

The COVID-19 pandemic has resulted in major shifts in the epidemiology of childhood infections. Respiratory syncytial virus (RSV) is a common cause of respiratory infections and bronchiolitis in children but its epidemiology has been transformed by pandemic-related lockdowns.1 RSV typically causes seasonal epidemics during winter. During the 2020 Australian winter, RSV infections decreased considerably; however, unseasonal RSV outbreaks occurred in spring 2020 in New South Wales2 and Western Australia.3 Following a more protracted lockdown in Victoria, an unseasonal rise in RSV occurred in early 2021, coinciding with school return following summer holidays.4 Several studies reviewed total numbers of positive RSV polymerase chain reactions in outpatients and inpatients, but did not analyse hospital admissions and clinical burden. We examined the clinical burden of the unseasonal peak in RSV infection by comparing the cases requiring hospitalisation before and during the COVID-19 pandemic and the relationship with lockdown periods. Positive RSV polymerase chain reactions in children, aged 0–18 years, were identified between 1 January 2019 and 31 October 2021 at Austin Health, a large public hospital in Melbourne. Retrospective chart review for all children requiring admission was performed focusing on the need for respiratory or feeding support, or transfer to a tertiary centre. Over the 2.5-year period, there was a striking difference in the number and pattern of RSV admissions each year (Fig. 1). During 2019, the typical seasonal pattern, predominantly during winter, was seen with 58 children admitted. Summer 2020 reflected a similar pattern to early 2019 prior to the COVID-19 pandemic onset. The lockdown period in Melbourne was far more prolonged than other Australian states, from 25 March until December 2020, reflected in no RSV admissions. In January–March 2021, 53 children were admitted with an average length of stay of 2.7 days; 34 required respiratory or feeding support. There was a high rate of co-infection with 25 patients having RSV and another virus (22 with entero/rhinovirus and three with adenovirus). These unusual patterns of RSV infection mirror the impact of pandemic-related public health measures, highlighting the need for vigilance regarding post-lockdown surges in infectious diseases. The Austin Health Human Research Ethics Committee approved the study.