Survey shows COVID-19 infection rates in secondary schools significantly lower than Autumn term

London School of Hygiene & Tropical Medicine

The reduced rate of infections in schools in England could reflect the lower rates in the community.

The number of students in both primary and secondary schools testing positive for COVID-19 was lower in the most recent round of testing in the Schools Infection Survey (SIS) carried out between 5 – 21 May 2021, than in December 2020.

During the testing period of round 5, 0.65% of primary students tested positive for having current infection. 0.05% of secondary school students tested positive for having current infection, which was significantly lower than in the Autumn term of 2020. Current infection levels in staff were not possible to declare due to low numbers of staff testing positive.

SIS is jointly led by researchers from the London School of Hygiene & Tropical Medicine (LSHTM), Public Health England (PHE) and the Office for National Statistics (ONS), and is funded by the Department for Health and Social Care (DHSC).

It aims to examine the prevalence of current infection and antibodies for SARS-CoV-2 among staff and students in England, monitor COVID-19 related absences, and assess implementation of measures by schools to control the virus, through valuable collaboration between scientists, school staff, pupils and parents.

The researchers carried out the testing in 142 schools within 11 local authority areas, 92% (131) of which returned no positive cases. 11 schools returned one or two cases, eight of which were located in the North West of England, where many of the schools participating in the survey were located.

The proportion of primary and secondary schools school staff testing positive for SARS-CoV-2 antibodies was 24.4% and 21.8% respectively – in comparison with 21.5% of primary school staff and 18.7% of secondary school staff in March 2021 (round 4). This suggests continued growth in school staff developing natural immunity to COVID-19, as the testing in SIS only detects antibodies produced following natural infection.

Despite oversampling in the North West of England, where the Delta variant was most prevalent in May, the researchers found low numbers of positive cases of that variant. The majority of cases in round 5 (84%) were compatible with the Alpha variant, compared to 96% in round 4.

The researchers also measured seroconversion rates – the rate at which individuals change from testing negative for antibodies to testing positive, indicating infections that occur between testing rounds.This was significantly lower between round 4 and 5 in primary school staff (1.4 per 1,000 person weeks) than the seroconversion rates seen between round 2 (December 2020) and round 4 of testing. The secondary staff seroconversion rates between round 4 and 5 (2.1 per 1,000 person weeks) was not statistically different to those between round 1 (November 2020) and round 2, or between round 2 and 4.

At the time of this round of testing, 86.6% of staff have received at least one dose of a COVID-19 vaccine – up from 62.9% at the end of March – and 43.1% had received both doses – up from 1.0% at the end of March. When split by age groups, over 90% of staff members aged 35-49 had received at least one dose by the end of May, at which point vaccination rates showed less variation by local authority than they did at the end of March.

Professor James Hargreaves, co-chief investigator of the study at LSHTM, said: “Current infection rates in schools have reduced since the Autumn. This is encouraging, and is likely to be partly reflective of the reduced rates in the local communities, as well as the measures put in place by schools to protect their staff and students. It is also encouraging to see good take up of the vaccine program among school staff.”

The researchers also carried out a survey of anticipated uptake of COVID-19 vaccines by parents of children under the age of 16. They received 4,439 responses between 12 – 21 May, of which 42% of primary school parents and 53% of secondary school parents said they would definitely vaccinate their child. Only 4% and 3% of parents of primary and secondary school parents, respectively, said “Definitely no” when asked if they would vaccinate their child.

The most common reasons parents gave for responding “Definitely no” were: not enough research has been carried out; wanting more information on long term side-effects; and concerns about vaccine safety and side-effects.

Dr Shamez Ladhani, Consultant Paediatrician at PHE and study lead said: “COVID-19 infection rates in staff and students remained low following the full reopening of schools in March, compared to the autumn term.

“Reassuringly, more than 85% of staff have received at least one dose of a vaccine and it’s hoped that they will soon receive a second dose, playing a key role in reducing the risk of COVID-19 in schools.

“These results are a strong indicator that measures in schools are working to limit transmission. As schools continue to reflect what is happening in the community, regular testing has helped to stop the virus from entering schools.”

Alison Judd, Head of Schools Infection Survey Analysis, said: “Results show that after the wider re-opening of schools in March up until the antibody tests carried out in mid-May, the rate of infection among staff was at its lowest for this academic year.

“We have nearly finished the last round of testing – and I would like to say a huge thank you to all of our participants and the school’s involved for their help with making the study possible.”

The researchers acknowledge that this study is designed to oversample schools in areas of England where COVID-19 infection was highest at the start of the academic year, so the data are not applicable to all schools in England. Additionally, response rates were low, particularly amongst students.

SIS is conducted using PCR tests and is independent to the mass asymptomatic testing programme in schools using lateral flow devices. Results are only available for those who enrolled in the survey and present at school on the day of testing.

*Round 1 of the survey took place between 3 and 19 November 2020 and Round 2 between 2 and 10 December 2020. Round 3, which was due to take place in late January 2021, was cancelled due to schools in England being closed to the majority of pupils during lockdown. Round 4 took place between 15 and 31 March 2021, and Round 5 between 5 and 21 May 2021.*

Publication

COVID-19 Schools Infection Survey, England: Round 5, England: May 2021

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