London School of Hygiene & Tropical Medicine

Data from the fourth round of the SIS – research jointly led by Public Health England (PHE), the Office for National Statistics (ONS) and the London School of Hygiene & Tropical Medicine (LSHTM) – tested 7,271 secondary school pupils and 2,744 staff for COVID-19 infection between 15 - 31 March. The results suggest infections fell significantly among both staff and pupils compared to previous findings in November and December 2020.

The latest study, which looked at schools from across 14 local authorities taking part, found that 0.34% of secondary school pupils tested positive for current infection (95% confidence interval: 0.16% to 0.63%) and 0.19% of secondary school staff tested positive for current infection (95% confidence interval: 0.04% to 0.58%).

In comparison to the first two rounds, which used data from schools across 11 local authorities in secondary schools, this study found the percentage of pupils testing positive (0.33%) was significantly lower than in Round 1 (1.42%) and lower than Round 2 (1.22%), and the percentage of staff testing positive (0.32%) was significantly lower than in Round 1 (1.36%) and Round 2 (1.64%). The number of positive test results in round four for primary schools was too small to present due to statistical disclosure criteria.

Dr Shamez Ladhani, Consultant Paediatrician at PHE and the study’s chief investigator, said: “Results of this study shows current COVID-19 infection among secondary school staff and pupils has fallen significantly from the already low levels recorded last November.

“These findings are reassuring and contribute to wider evidence that shows the risk of transmission in schools is low. This also indicates the importance of public health measures in schools for reducing transmission.”

Professor James Hargreaves, co-chief investigator of the study at LSHTM, said: "This round of testing took place just after schools in England fully reopened. The lower levels of infection compared to previous round is encouraging, possibly reflecting both lower community incidence and, perhaps, the roll-out of mass community-based testing.

“However, some schools did record positive cases so continued efforts are crucial to both limit infections entering schools and preventing transmission within the school site."

Fiona Dawe, Deputy Director, Wider Surveillance Studies at ONS, said: “The data shows that during round four of testing, there was a reduction in current infection rates in schools taking part in the study.  In secondary schools there was a significant reduction in current infection levels in both pupils and staff.

“As we see the vaccine rollout across the country, it’s essential that we continue testing for COVID-19 infection and antibodies in school settings. The Schools Infection Survey remains an important study in assessing the role of schools in the pandemic and how the virus is transmitted in school settings.

“I would like to thank all the staff and pupils who are taking part in the study for their continued participation, without which this important study would not be possible.”

The Schools Infection Survey 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.