Transmission of SARS-CoV-2 by children to contacts in schools and households: a prospective cohort and environmental sampling study in London

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Title: Transmission of SARS-CoV-2 by children to contacts in schools and households: a prospective cohort and environmental sampling study in London
Authors: Cordery, R
Reeves, L
Zhou, J
Rowan, A
Watber, P
Rosadas, C
Crone, M
Storch, M
Freemont, P
Mosscrop, L
Cowley, A
Zelent, G
Bisset, K
Le Blond, H
Regmi, S
Buckingham, C
Junaideen, R
Abdulla, N
Eliahoo, J
Mindlin, M
Lamagni, T
Barclay, W
Taylor, GP
Sriskandan, S
Item Type: Journal Article
Abstract: Background: Assessing transmission of SARS-CoV-2 by children in schools is of critical importance to inform public health action. We assessed frequency of acquisition of SARS-CoV-2 by contacts of pupils with COVID-19 in schools and households, and quantified SARS-CoV-2 shed into air and onto fomites in both settings. Methods: Incidents involving exposure to at least one index pupil with COVID-19 in 8 schools were identified between October 2020-July 2021 (prevailing variants, original, alpha and delta). Weekly PCR testing for SARS-CoV-2 was undertaken on immediate classroom contacts (the “bubble”), non-bubble school contacts, and household contacts of index pupils, supported by genome sequencing, and on surface and air samples from school and home environments. Findings: Secondary transmission of SARS-CoV-2 was not detected in 28 bubble contacts, representing 10 bubble classes (participation rate 8.8%, IQR 4.6-15.3%). Across 8 non-bubble classes, 3/62 pupils tested positive but these were unrelated to the original index case (participation rate 22.5%, IQR 9.7-32.3%). All three were asymptomatic and tested positive in one setting on the same day. In contrast, secondary transmission to previously-negative household contacts from infected index pupils was 17.1% (6/35) rising to 27.7% (13/47) when considering all potential infections in household contacts. Environmental contamination with SARS-CoV-2 was rare in schools; fomite SARS-CoV-2 was identified in 4/189 (2.1%) samples in bubble classrooms, 2/127 (1.6%) samples in non-bubble classrooms, and 5/130 (3.8%) samples in washrooms. This contrasted with fomites in households, where SARS-CoV-2 was identified in 60/248 (24.2%) bedroom samples, 66/241 (27.4%) communal room samples, and 21/188 (11.2%) bathroom samples. Air sampling identified SARS-CoV-2 RNA in just 1/68 (1.5%) of school air samples, compared with 21/85 (24.7%) of air samples taken in homes. Interpretation: There was no evidence of large scale SARS-CoV-2 transmission in schools with precautions in place. Low levels of environmental contamination in schools are consistent with low transmission frequency and suggest adequate cleaning and ventilation in schools during the period of study. The high frequency of secondary transmission in households associated with evident viral shedding throughout the home suggests a need to improve advice to households with infection in children in order to prevent onward community spread. The data suggest that SARS-CoV-2 transmission from children in any setting is very likely to occur when precautions are reduced.
Date of Acceptance: 29-Apr-2022
ISSN: 2666-5247
Publisher: Elsevier
Journal / Book Title: The Lancet Microbe
Copyright Statement: This paper is embargoed until publication. Once published it will be available fully open access.
Sponsor/Funder: UK Research and Innovation
Funder's Grant Number: MR/V028413/1
Publication Status: Accepted
Embargo Date: publication subject to indefinite embargo
Appears in Collections:Department of Infectious Diseases
Imperial College London COVID-19
School of Public Health