Epidemiology of respiratory syncytial virus in children younger than 5 years in England during the COVID-19 pandemic, measured by laboratory, clinical, and syndromic surveillance: a retrospective observational study

Background Seasonal epidemics of respiratory syncytial virus (RSV) cause a clinically significant burden of disease among young children. Non-pharmaceutical interventions targeted at SARS-CoV-2 have affected the activity of other respiratory pathogens. We describe changes in the epidemiology of RSV among children younger than 5 years in England since 2020.Methods Surveillance data on RSV infections, comprising laboratory-confirmed cases, proportion of positive tests, hospital admissions for RSV-attributable illness, and syndromic indicators for RSV-associated disease (emergency department attendances for acute bronchitis or bronchiolitis, non-emergency health advice telephone service [NHS 111] calls for cough, general practitioner [GP] in-hours consultations for respiratory tract infections, and GP out-of-hours contacts for acute bronchitis or bronchiolitis) were analysed from Dec 29, 2014 to March 13, 2022, for children younger than 5 years. Data were extracted from national laboratory, clinical, and syndromic surveillance systems. Time-series analyses using generalised linear models were used to estimate the effect of non-pharmaceutical interventions targeting SARS-CoV-2 on RSV indicators, with absolute and relative changes calculated by comparing observed and predicted values.Findings RSV-associated activity was reduced for all RSV indicators during winter 2020-21 in England, with 10 280 (relative change -99middot5% [95% prediction interval -100middot0 to -99middot1]) fewer laboratory-confirmed cases, 22middot2 (-99middot6%) percentage points lower test positivity, 92 530 (-80middot8% [-80middot9 to -80middot8]) fewer hospital admissions, 96 672 (-73middot7% [-73middot7 to -73middot7]) fewer NHS 111 calls, 2924 (-88middot8% [-90middot4 to -87middot2]) fewer out-of-hours GP contacts, 91 304 (-89middot9% [-90middot0 to -89middot9]) in-hours GP consultations, and 27 486 (-85middot3% [-85middot4 to -85middot2]) fewer emergency department attendances for children younger than 5 years compared with predicted values based on winter seasons before the COVID-19 pandemic. An unprecedented summer surge of RSV activity occurred in 2021, including 11 255 (1258middot3% [1178middot3 to 1345middot8]) extra laboratory-confirmed cases, 11middot6 percentage points (527middot3%) higher test positivity, 7604 (10middot7% [10middot7 to 10middot8]) additional hospital admissions, 84 425 (124middot8% [124middot7 to 124middot9]) more calls to NHS 111, 409 (39middot0% [36middot6 to 41middot8]) more out-of-hours GP contacts, and 9789 (84middot9% [84middot5 to 85middot4]) more emergency department attendances compared with the predicted values, although there were 21 805 (-34middot1% [-34middot1 to -34middot0]) fewer in-hours GP consultations than expected. Most indicators were also lower than expected in winter 2021-22, although to a lesser extent than in winter 2020-21.Interpretation The extraordinary absence of RSV during winter 2020-21 probably resulted in a cohort of young children without natural immunity to RSV, thereby raising the potential for increased RSV incidence, out-of-season activity, and health-service pressures when measures to restrict SARS-CoV-2 transmission were relaxed.Copyright (c) 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license.

Automated summary

This study describes the epidemiological changes of respiratory syncytial virus (RSV) among children under 5 years old in England since 2020. The study found that RSV activity was significantly reduced during the winter of 2020-21, but an unprecedented summer surge occurred in 2021. Rating: 9/10.