Effects of public health measures during the SARS‐CoV‐2 pandemic on the winter respiratory syncytial virus epidemic: An interrupted time series analysis

BACKGROUND: Public health measures (PHM) designed to contain the spread of COVID-19 pandemic have influenced the epidemiological characteristics of other viral infections. Its impact on acute RSV bronchiolitis in infants of ≤24 months old has not been systematically studied in our setting. OBJECTIVES: To describe the monthly pattern of visits to the Paediatric Emergency Department (PED) of patients 0 to 14 years of age, the rate of patients diagnosed with RSV acute bronchiolitis per thousand inhabitants of 0 to 24 months, and the rate of them requiring hospital admission during the winter 2020-2021, in the context of local and national COVID-19 restrictions and compare them to the four previous seasons. METHODS: Interrupted time series analysis of patients assisted in the PED and diagnosed with or admitted for RSV acute bronchiolitis in a tertiary University Hospital from January 2016 to February 2020 (pre-intervention period) and from March 2020 to June 2021 (post-intervention period). INTERVENTION: Preventive PHM implemented by the Spanish government weighted by the Containment and Health Index of the Oxford COVID-19 Government Response Tracker. RESULTS: The intervention was followed by an immediate reduction of the rate of visits to the PED of -19.5 (95% confidence interval [CI] -24.0, -14.9) per thousand, and the rate of diagnoses and admissions for RSV acute bronchiolitis of -44.3 (95% CI -73.8, -14.8) and -1.4 (95% CI -2.7, -0.1) per thousand, respectively, with a delayed rebound. CONCLUSIONS: After the implementation of PHM to prevent the spread of SARS-CoV-2 infection, an immediate and important decline in the visits to the PED was observed, with an upward change thereafter. There was also an initial reduction in the diagnoses of and admissions by RSV acute bronchiolitis. An upward trend was observed six to nine months after the usual time of the winter RSV epidemic, coinciding with the relaxation of the preventive PHM.