ABSTRACT
BackgroundThe role of children and staff in SARS-CoV-2 transmission outside and within households is still not fully understood when large numbers are in regular, frequent contact in schools. MethodsWe used the self-controlled case-series method during the alpha- and delta-dominant periods to explore the incidence of infection in periods around a household member infection, relative to periods without household infection, in a cohort of primary and secondary English school children and staff from November 2020 to July 2021. ResultsWe found the relative incidence of infection in students and staff was highest in the 1-7 days following household infection, remaining high up to 14 days after, with risk also elevated in the 6-12 days before household infection. Younger students had a higher relative incidence following household infection, suggesting household transmission may play a more prominent role compared with older students. The relative incidence was also higher amongst students in the alpha variant dominant period. ConclusionsThis analysis suggests SARS-CoV2 infection in children, young people and staff at English schools were more likely to be associated with within-household transmission than from outside the household, but that a small increased risk of seeding from outside is observed. Key messagesO_LIQuestion: With respect to incidence of SARS-CoV-2 infection before and after household member infection, is within-household transmission more likely than community transmission amongst school children and staff? C_LIO_LIFindings: In this self-controlled case-series analysis, the relative incidence of infection in students and staff was highest in the 1-7 days following household infection, remaining high up to 14 days after, with the highest relative incidence found in younger, primary school-aged children. C_LIO_LIImportance: Within-household transmission is more likely than from outside the household, but a small increased risk of seeding from outside the household is observed as well as variation by age and variant dominant period. C_LI
Subject(s)
COVID-19 , Severe Acute Respiratory SyndromeABSTRACT
Background Risk factors for infection and, therefore, antibody positivity rates will be different in children compared to adults. We aim to estimate national and regional prevalence of SARS-CoV-2 antibodies in primary (4-11-year-olds) and secondary (11-15-year-olds) school children between 10 November and 10 December 2021. Methods Cross-sectional surveillance in England using two stage sampling, firstly stratifying into regions and selecting local authorities, then selecting schools according to a stratified sample within selected local authorities. Participants were sampled using a novel oral fluid validated assay for SARS-CoV-2 spike and nucleocapsid IgG antibodies. Results 4,980 students from 117 state-funded schools (2,706 from 83 primary schools, 2,274 from 34 secondary schools) provided a valid sample. After weighting for age, sex and ethnicity, and adjusting for assay accuracy, the national prevalence of SARS-CoV-2 antibodies in primary school students, who were all unvaccinated, was 40.1% (95%CI; 37.3-43.0). Antibody prevalence increased with age (p<0.001) and were higher in urban than rural schools (p=0.01). In secondary school students, the adjusted, weighted national prevalence of SARS-CoV-2 antibodies was 82.4% (95%CI; 79.5-85.1); including 57.5% (95%CI; 53.9-61.1) in unvaccinated and 97.5% (95%CI; 96.1-98.5) in vaccinated students. Antibody prevalence increased with age (p<0.001), and was not significantly different in urban versus rural students (p=0.1). Conclusions Using a validated oral fluid assay, we estimated national and regional seroprevalence of SARS-CoV-2 antibodies in primary and secondary school students. In November 2021, 40% of primary school students and nearly all secondary school students in England had SARS-CoV2 antibodies through a combination of natural infection and vaccination.
ABSTRACT
Background: Following the full re-opening of schools in England and emergence of the SARS-CoV-2 Alpha variant, we investigated the risk of SARS-CoV-2 infection in students and staff who were contacts of a confirmed case in a school bubble (school groupings with limited interactions), along with their household members. Methods: Primary and secondary school bubbles were recruited into sKIDsBUBBLE after being sent home to self-isolate following a confirmed case of COVID-19 in the bubble. Bubble participants and their household members were sent home-testing kits comprising nasal swabs for RT-PCR testing and whole genome sequencing, and oral fluid swabs for SARS-CoV-2 antibodies. Results: During November-December 2020, 14 bubbles were recruited from 7 schools, including 269 bubble contacts (248 students, 21 staff) and 823 household contacts (524 adults, 299 children). The secondary attack rate was 10.0% (6/60) in primary and 3.9% (4/102) in secondary school students, compared to 6.3% (1/16) and 0% (0/1) among staff, respectively. The incidence rate for household contacts of primary school students was 6.6% (12/183) and 3.7% (1/27) for household contacts of primary school staff. In secondary schools, this was 3.5% (11/317) and 0% (0/1), respectively. Household contacts were more likely to test positive if their bubble contact tested positive although there were new infections among household contacts of uninfected bubble contacts. Interpretation: Compared to other institutional settings, the overall risk of secondary infection in school bubbles and their household contacts was low. Our findings are important for developing evidence-based infection prevention guidelines for educational settings.