Assessing the clinical and socio-economic burden of RSV in children under 5 years in primary care: Protocol for a prospective cohort study in England and report on adaptations of the study to the COVID-19 pandemic.

BACKGROUND: Respiratory syncytial virus (RSV) commonly causes lower respiratory tract infections (LRTI) and hospitalisation in children. In 2019-2020, the Europe-wide RSV ComNet standardised study protocol was developed to measure the clinical and socio-economic disease burden of RSV infections amongst children <5 years of age in primary care. RSV has a recognised seasonality in England. OBJECTIVE: 1. Describe adaptations of RSV ComNet standardised study protocol for England, and 2. Describe the challenges of conducting the study during the COVID-19 pandemic. METHODS: The study was conducted by the Oxford-Royal College of General Practitioners (RCGP) Research and Surveillance Centre (RSC), the English national primary care sentinel network. We invited all general practices within the network that undertook virology sampling (N=248 general practices, registered population 3,056,583) to participate in the study by recruiting eligible patients. Children <5 years old with the following case definition of RSV infection were included in the study:, consulting a health care practitioner in primary care with symptoms meeting the World Health Organisation's (WHO) definition of acute respiratory illness (ARI) or influenza like illness (ILI), who have laboratory confirmed RSV infection. Parents/guardians of cases were asked to complete two, previously validated, questionnaires (day 14 and 30 post-sampling). A sample size of at least 100 RSV+ cases is required to estimate the percentage of children that consult in primary care who need hospitalization. Assuming a swab positivity rate of 20% in children <5 years, we estimate we require 500 swabs. We adapted our method for the pandemic by extending sampling planned for winter 2020-2021 to a rolling data collection, allowing verbal consent and introducing home-swabbing because of increased virtual consultations during the COVID-19 pandemic. RESULTS: Preliminary results of the data collection between International Standards Organisation (ISO) weeks 1 to 41 2021 are described. There was no RSV detected in the winter of 2020-2021 through the study. The first positive RSV swab collected through the sentinel network in England was collected in ISO week 17, 2021 and then every week since ISO week 25. Sixteen (16/248=6.5%) of the virology sampling practices volunteered to participate. These 16 practices are high sampling practices collecting the majority of eligible swabs across the sentinel network, namely 200 out of the 457 swabs (43.8%) of which 54 (54/200=27%) were positive for RSV. CONCLUSIONS: Measures to control the COVID-19 pandemic meant there was no circulating RSV last winter, however RSV has circulated out of season, detected by the sentinel network. Whilst the sentinel network practices have collected 40% (200/500) of the required samples and 27% (54/200) were RSV positive. We have demonstrated the feasibility of implementing a European-standardised RSV Disease Burden study protocol in England during a pandemic, and now need to recruit to this adapted protocol. CLINICALTRIAL: Not applicable. INTERNATIONAL REGISTERED REPORT: DERR1-10.2196/38026.