4 September 2023
Date: September 2021
The Covid-19 Schools Infection Survey (SIS) was implemented and delivered at pace in Autumn 2020 in England in response to the government’s need for data about the pandemic. The survey assessed SARS-CoV-2 infection and transmission within school settings. It is one of the largest and most comprehensive longitudinal research studies undertaken globally in primary and secondary schools during the pandemic.
The Covid-19 SIS informed government strategies to keep schools open safely during the earlier parts of the pandemic and reduce the collateral impact of school closures on educational attainment. It also informed vaccine recommendations, and the later decisions to re-open schools.
SIS was developed in partnership between the London School of Hygiene and Tropical Medicine, the ONS and UK Health Security Agency (UKHSA). The survey was used to:
- estimate the incidence of SARS-CoV-2 seroconversion (antibody negative to antibody positive) among children and staff
- measure the prevalence of current SARS-CoV-2 infection among children and staff
- monitor student and staff attendance rates in a sample of schools, and the proportion of and reasons for school closure
- assess the feasibility, acceptability and experience of school implementation of SARS-CoV-2 control measures
- conduct detailed investigations of selected outbreaks occurring in schools to determine the risk of transmission within and between classes and schools, and between students, staff and other household members.
The survey was recommissioned in September 2021 to continue to provide insight into infection and transmission in schools, and with a particular focus on school recovery and resilience.
Methods used to collect data
The Covid-19 SIS was a multisite, prospective, observational cohort study conducted in a random sample of primary and secondary schools in selected local authorities in England. Six bio-behavioural surveys were planned among participating students and staff between November 2020 and July 2021. A total of 22,585 individuals:
- 1,891 staff and 4,654 students from 59 primary schools, and
- 5,852 staff and 10,188 students from 97 secondary schools
participated in at least one survey.
The study involved a number of data collection measures:
- Repeated in-school collection of biological samples to capture current and past infection: During in school visits the research team collected nasal swabs for real-time polymerase chain reactions (“real-time PCR”) testing for current SARS-CoV-2 infection, antibody testing among students using an innovative in-house oral fluid assay developed by UKHSA, and self-collected capillary blood samples for antibody testing among staff.
- Online questionnaires and follow-up studies
- Linkage to routine data sources collected data on student and staff school attendance rates, feasibility, and acceptability of school-level implementation of SARS-CoV-2 control measures and investigation of selected school outbreaks, Test and Trace data and immunisation data.
When the survey was recommissioned in September 2021, new and some existing schools were selected to be nationally representative. Three waves of oral fluid antibody samples were collected over the autumn and spring school terms. A broader range of questionnaire data was introduced to understand factors affecting vaccine uptake, other mitigation measures and longer-term health impacts of Covid-19 and school closure on pupils and the schools.
The researchers estimated SARS-CoV-2 infection prevalence among staff and students attending school, antibody prevalence and conversion rates between testing rounds. The team compared the findings with other national studies on children and adults.
Within the context of high levels of ongoing community-based transmission during September-December 2020, the overall prevalence of current SARS-CoV-2 infection among staff and students present on the school campus on normal school days (those who were asymptomatic at the time of testing) was found to be 0.7-1.6%.
Over that school year, antibody prevalence rose among staff and students. During April-July 2021, a mass asymptomatic testing programme had been introduced for school staff and secondary school students, in addition to a range of existing measures.
Findings from this research study suggest that the epidemiology of SARS-CoV-2 among school populations varied with community transmission. Findings were consistent with the hypothesis that “school gate” control measures in place during 2020-21 may have partially reduced the risk of those with prevalent infection attending school.
The team examined individual, household, community, and school-level risk factors for SARS-CoV-2 infection using mixed-effect logistic-regression models. The researchers integrated the data with a model that incorporated pre-pandemic social interactions and pandemic-era interventions to exploring how different interventions shaped the dynamics of outbreaks among school children. In the second year, initial findings noted the importance and rapid mitigation measures put in place by schools (when more stringent earlier measures were relaxed). These included: school ventilation measures, response to inequalities in vaccine receipt and vaccine hesitancy in parents, support for long covid in children and young people and mental health systems for staff and students.
The Covid-19 School Infection Surveys represent a critical source of information which has informed guidance from the Scientific Advisory Group for Emergencies (SAGE) and decision making by the Department for Health and Social Care.
Research outputs from SIS were a core component of the approaches informing policies to keep schools open safely in the earlier parts of the pandemic. They also informed factors supporting recovery during the main period, reducing collateral impacts of the pandemic on children’s educational attainment and wellbeing.
The data collected by SIS in the second half of the 2021 spring term, shortly after schools reopened following national lockdown, was key to the government’s assessment of risk and planning for the ongoing policy that kept schools open. Knowledge of the lower antibody levels in young children in late Autumn 2021 was also crucial, as this informed vaccine recommendations.
Similarly, data around implementation of Covid-19 preventative measures has been widely used across government in their approach to managing the ongoing risk of infection and transmission in schools, particularly at the start of the new academic year in September 2021.
The rich dataset generated will also provide useful insights for future pandemic preparedness.
Publications and reports
- National Library of Medicine publication, April 2021: The COVID-19 Schools Infection Survey in England: Protocol and participation profile for a prospective, observational cohort study
- London School of Hygiene and Tropical Medicine survey results: Schools Infection Survey 2
- ONS statistical bulletin, February 2022: COVID-19 Schools Infection Survey, England: attitudes to vaccines and preventative measures, November to December 2021
- ONS statistical bulletin, February 2022: COVID-19 Schools Infection Survey, England: mental health and long COVID, November to December 2021
- ONS statistical bulletin, February 2022: COVID-19 Schools Infection Survey, England: pupil antibody data, November to December 2021
- ONS, July 2022: COVID-19 Schools Infection Survey: methods and further information
Blogs, news posts, and videos
- Schools Week news article, July 2022: Why Schools’ pandemic lessons are not just for the children
- LSHTM news article, May 2022: Over half of secondary school students struggle with motivation as a result of remote learning
- LSHTM news article, February 2022: School survey shows over half of primary school parents likely to agree to their child being vaccinated
- LSHTM news article, June 2022: Majority of school students in England now have antibodies against COVID-19
Presentations and awards
- Research Excellence, ONS Research Excellence Awards 2022
- People’s Choice, ONS Research Excellence Awards 2022
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