SIS is a study taking place in 150 schools across 15 local authorities in England in 2020 to 2021, investigating the role of schools in the spread of COVID-19 and how transmission within and from schools can be minimised.
SIS is conducted by the London School of Hygiene & Tropical Medicine, in conjunction with the Office for National Statistics, the Department of Education, the Department of Health & Social Care and Public Health England.
The Schools Infection Survey (SIS) is a flagship study investigating the role of schools in the spread of COVID-19.
The coronavirus pandemic has had a major impact worldwide, and spread of the infection within and from schools has been a concern throughout this time. SIS was established to assess transmission of COVID-19 within and from school settings, to examine mitigation measures aimed at minimising transmission and mental health factors related to the pandemic.
The study is being carried out by the London School of Hygiene & Tropical Medicine together with partners at Public Health England and the Office for National Statistics. Working alongside the Department for Education and the Department for Health and Social care, the study is collecting data from students and teachers at 150 schools in 15 Local Authorities in England.
The study is collecting nose swabs, saliva samples and blood samples, looking for the presence of the COVID-19 virus as well as for antibodies against the virus. Antibodies are produced as your body is fighting an infection, whether you develop symptoms or not, and even after you’ve recovered, antibodies remain in your blood at low levels for some time. If you encounter the same virus again, these antibodies respond to it quickly, and you tend not to become sick again, or have a much less severe illness.
One main aim of SIS is to look at what’s called seroconversion. This is a word that describes someone who starts out without antibodies to COVID-19, but has antibodies when tested at a later date. This change indicates that someone has had a COVID-19 infection. In some cases the person may never have felt sick or have had any symptoms – this is called an asymptomatic infection. Many people have had COVID-19 but never had any symptoms, and this contributes to the spread of the virus. The nose swab tests also provide a snapshot of the number of people with an asymptomatic infection on a given school day.
In addition to taking samples, we ask participants in the study to fill out questionnaires. These provide us with lots of information that we can combine with the results of the tests, and help us get a clearer picture of exactly what is going on with participants in the study.
The first round of the study took place in November 2020 during the autumn term, and looked at 105 schools in 14 local authorities. This round had 11,194 participants comprising 4,941 staff and 6,253 students.
Findings from the first round focused on rates of current infection.
This first round of data showed that the proportion of students testing positive for current COVID-19 infection was 1.24%, with 1.29% of staff testing positive. This was roughly the same as levels found in the wider community at the peak of the second wave of the pandemic. The proportion testing positive for current infection in the community was 1.2% during the week 8 November to 14 November 2020.
Round 2 took place while schools were still open in December 2020, and looked at both infection rates and antibody rates.
The results showed that the proportions of staff and students testing positive for current COVID-19 infection were lower than those measured in the community. Testing only included people in school on testing day, however, so anyone isolating at home with symptoms was excluded from testing data as a result.
The proportion of school staff testing positive for antibodies was similar to other working age adults in the community. There was little evidence to suggest that participating school staff are at greater risk of infection than other working adults, although response rates were low.
Schools have been working hard to put in place control measures to keep staff and students safe. Almost all schools in this sample implemented control measures strongly recommended by the Department of Education.
These control measures included efforts to ensure symptomatic individuals stayed at home, enhanced cleaning and hygiene protocols, limiting gatherings, and staff distancing from other adults.