Wearing masks in the classroom helps stop the spread of Covid-19 in schools, according to a new study.
And the findings suggest that requiring school staff and students to wear masks could help reduce the need to close schools as part of lockdowns to stop the transmission of the coronavirus.
Mandatory face masks in different settings has been one of the most controversial elements of the pandemic, causing feelings to run high among both those opposed to wearing masks and those in favor.
But school closures have disrupted education for millions around the world, causing a range of adverse consequences for children including poor nutrition and social isolation, as well as loss of learning.
So evidence of viable alternatives to school closure will be seen as a hugely positive step forward in efforts to try to contain the virus.
The study looked at the impact of a number of measures, including mask wearing, on transmission of the virus in schools and preschools in the state of Mecklenbury-Western Pommerania in north-eastern Germany, in research led by the University Hospital Rostock in Germany.
Researchers found that while children were predominantly the source of Covid-19 outbreaks in schools, outbreaks were more severe when an adult was the source, or index case.
But the number of secondary cases was significantly reduced if teachers and other school staff were wearing a mask, helping to prevent outbreaks, according to the study, published in the journal Frontiers in Public Health.
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“To avoid school closures at high incidence levels, it is important to identify factors contributing to the spread of Covid-19 infections in schools and preschools,” said Dr Anika Kästner, of the University Medicine Greifswald, Germany and co-author of the report.
Researchers looked at the incidence of Covid-19 infection in schools and preschools in two phases when schools were open: when there was no requirement to wear masks, and when staff and students were required to wear masks.
They found that when there was no obligation to wear masks, adult index cases caused 4.5 secondary cases on average, while child index cases caused an average of 0.3 secondary cases.
But when masks were obligatory the number of secondary cases caused by an adult index case fell to 0.5, while for child index cases it remained at 0.3 secondary cases.
In preschools, where just the adults were required to wear masks, secondary cases caused by adult index cases rose from 0.6 before mask-wearing became obligatory to 2.6 cases with masks. Researchers put this down to the prevalence in the mask-wearing phase of the delta variant, which caused more infections in children.
Secondary cases in preschools where children were the index case stood at 0.5 both before and after masks were made compulsory.
This suggests that wearing masks, particularly among teachers and other school staff, can have a significant role in stopping the spread of the virus and keeping schools open.
“Our results show that mandatory masking of teachers and caregivers and children at schools in the 2020 to 2021 school year each resulted in a significant reduction in the number of Covid-19 transmissions,” said Dr. Martine Sombetzki, from the University Hospital Rostock and lead author of the study.
There are a number of caveats to the study, not least of which is that the research was undertaken before the emergence of the more transmissible Omicron strain of the virus, and as yet it is unclear what difference that would make.
The study also did not account for the effect of vaccinations, which are not systematically registered in Germany, and also assumed that schools implemented hygiene measures, such as regular hand-washing.
Nevertheless, the study shows that wearing masks works in limiting the spread of coronavirus, said Kästner.
“Mask obligation, for adults in particular, was shown to be effective in reducing secondary cases,” she said.
“We can therefore recommend all-time mandatory masking in schools for both children and adults. In preschools, mask wearing could also reduce secondary cases,”