Respiratory syncytial virus outbreak during the COVID-19 pandemic. How has it changed?

Introduction:The epidemiology of respiratory syncytial virus (RSV) infection has changed during the COVID-19 pandemic. Our objectives were to describe the RSV epidemic in 2021 and compare it with the previous years to the pandemic. Methods:Retrospective study performed in Madrid (Spain) in a large pediatric hospital comparing the epidemiology and clinical data of RSV admissions during 2021 and the two previous seasons. Results:899 children were admitted for RSV infection during the study period. During 2021, the outbreak peaked in June and the last cases were identified in July. Previous seasons were detected in autumn-winter. The number of admissions in 2021 was significantly lower than in previous seasons. There were no differences between seasons regarding age, sex or disease severity. Conclusion:RSV hospitalizations during 2021 in Spain moved to summer with no cases in autumn and winter 2020-2021. Unlike other countries, clinical data were similar between epidemics.