Compulsory mask wearing helps reduce Covid-19 transmission in schools to below levels seen in the … [+]
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Schools are not key drivers of Covid-19 transmission, according to a study that strengthens the case for full re-opening.
Researchers found fewer than one in 20 Covid-19 infections among students and staff were acquired in schools and there were no recorded instances of child-to-adult transmission in school, even when the coronavirus was widespread in the community.
With millions of children out of school around the world, the findings provide evidence that fully reopening schools may not necessarily lead to a spike in cases.
But there is an important caveat to the research: the schools taking part had extensive safety measures in place, including adults and children wearing masks, regular hand-washing and maintaining physical distancing.
The study saw researchers from Duke University examine Covid-19 transmission in 11 North Carolina school districts with more than 90,000 K-12 students, over a nine week period that schools were open for in-person teaching between August and October last year.
None of the school districts taking part in the study had to close as a result of Covid-19 outbreaks during the nine week period.
The period covered by the study saw considerable community transmission, with each of the participating school districts seeing one to two new cases a week, and residents infecting slightly more than one other individual over the nine weeks.
Molecular testing on Covid-19 cases reported in the school districts found there were 773-community acquired infections over the nine weeks, according to the study, published in the journal Pediatrics.
If secondary transmission within schools were as common as within the wider community, researchers would have expected another 800-900 secondary infections within the schools.
But testing revealed there were only 32 within-school transmissions over the nine week period.
There were no instances of child-to-adult transmission reported in the schools taking part.
Across the 11 school districts taking part in the study, six had no secondary infections, two had one case and three had multiple cases.
Of the 32 confirmed within-school transmissions, there were six in pre-K settings, 11 in elementary schools, six in middle schools, five in high schools and four in K-12 schools.
An important factor in the lack of within-school transmission was the safety measures in place, said the researchers, Professor of Pediatrics Dr Danny Benjamin and Associate Professor of Pediatrics Dr Kanecia Zimmerman.
These included mask wearing at all times for all children aged five and over, apart from during meals or when sufficiently distanced outside.
The schools also operated a six foot (two metre) physical distancing measure, and encouraged students to wash their hands regularly.
In addition, school superintendents reported several other steps that contributed towards low transmission rates, including daily screening of students and staff, transparency in reporting new cases and efficient contract tracing.
While closing schools has been a widely-used strategy to try to contain the spread of the coronavirus, the researchers said there was previously little data on transmission in schools that took steps to limit infections, such as wearing masks.
‘Our data support the concept that schools can stay open safely in communities with widespread community transmission,’ they said.
Most cases of secondary transmission in the school districts were related to not wearing face masks, the researchers said.
This was particularly apparent in special needs education, where masking was not always feasible, they added.
They also noted that the policy of requiring individuals to quarantine if they spent 15 minutes or more within six feet of someone who later tested positive was counter-productive if everyone was wearing masks.
Transmission in masked settings was uncommon, it sends a mixed message about the benefits of masking and professionals in other environments, such as hospitals, do not have to quarantine if they have been caring for asymptomatic parents while masked, the researchers said.
The findings strengthen the case to fully reopen schools, as much for children’s mental health as for their education, although this will also prove controversial at a time when cases are still high and health services are struggling to cope.
All schools in England have been closed to most students since Christmas, but Prime Minister Boris Johnson said today that students could begin to return on March 8.
