The Impact of the COVID-19 Pandemic on the Timing, Age and Severity of Respiratory Syncytial Virus (RSV) Emergency Presentations, a Multi[1]Centre Prospective Observational Cohort Study Extension.

Primary Objective – To report the timing, frequency and clinical severity of RSV infection in children under two years of age presenting to paediatric hospitals in the UK and Ireland.

This is a convenience sample cohort study and as such a sample size is not calculated. Recruitment will remain open until at least 31 December 2021. It is anticipated this will enroll a minimum sample size of 3,000 children attending ED. Approximately 10-20% of children attending ED under two years of age with acute bronchiolitis/wheeze are admitted to hospital for continuing care. During an RSV season, approximately 60-85% of admitted cases are RSV positive. Previous surveillance studies have recruited > 1000 patients in short time scales (1-2 months) with no additional funding. A large wave of bronchiolitis followed for a year may well achieve large sample size numbers.