Respiratory Syncytial Virus and Influenza Surveillance in Schoolchildren Seen at a Children's Hospital over 2 Months of the Second Semester of 2021.

Introduction. Reporting of respiratory infections reduced during the COVID-19 pandemic. The objective was to estimate the prevalence of respiratory syncytial virus(RSV)and influenza in schoolchildren seen at a children's hospital during the return to school. Methods. Cross-sectional study of patients aged 3-18 years suspected of COVID-19 with a negative test for SARS-CoV-2 between August and October 2021. Participants were stratified by level of education. PCR was used to detect RSV and influenza. Results. A total of 619 children were included: 234 in preschool, 224 in primary and 161 in secondary school; 25.5% (158) tested positive for RSV (36.3% in the pre-school level versus 21% in primary and 16% in secondary school). Infection among adolescents was associated with school contact with symptomatic cases (OR 2.5; 95%CI 1-6.80; p = 0.04). No case of influenza was detected. Conclusion. RSV was isolated in one fourth of the study population, with a higher frequency in pre-school; among adolescents, it was associated with school contact with symptomatic cases. No case of influenza was detected.