Back in April, the French epidemiologist Arnaud Fontanet found himself leading an investigation in the town of Crépy-en-Valois, a small community of 15,000 inhabitants just to the north-east of Paris. In February, the town’s middle and high schools had become the centre of a new outbreak of Covid-19.
Fontanet and colleagues from the Pasteur Institute in Paris were tasked with conducting antibody testing across Crépy-en-Valois to understand the extent to which the virus had been circulating. As they surveyed the town, they noted an interesting pattern. While the virus had spread rampantly through the high school, with 38% of students being infected, along with 43% of teachers and 59% of non-teaching staff, the same was not true for the town’s six primary schools. While three primary-age pupils had caught Covid-19 in early February, none of these infections had led to a secondary case. Overall, just 9% of primary age pupils, 7% of teachers and 4% of non-teaching staff had been infected with the virus.
“These results showed us that teenagers are just as contagious as adults,” said Fontanet. “But in the younger age groups, it’s a different story. They do not seem to transmit it to the same extent.”
Similar findings have emerged elsewhere. A new epidemiological study of 65,000 people in South Korea, which traced contacts of people infected between late January and late March, has revealed that while children aged 10-19 can spread the virus just as well as adults, those younger than 10 transmit it to others much less often.Advertisementhttps://tpc.googlesyndication.com/safeframe/1-0-37/html/container.html
“It looks like children overall have a transmission efficiency of about 50% of adults, although that varies dramatically across age groups,” says Susan Coffin, an infectious disease physician at the Children’s Hospital of Philadelphia. “As children enter their teens, the transmission efficiency begins to approach that of adults.”
There are worries that masks could lead to behavioural problems
Potential reasons for this abound. Some have suggested that young children have a lower viral load than teenagers and adults – although the evidence for this remains somewhat unclear – or that they exhale less air, so reducing their chances of passing on the virus.
Perhaps more simply, it may just be that the vast majority of young children tend to be either asymptomatic or have very mild symptoms when they contract Covid-19. In one of the largest studies of paediatric Covid-19 patients, based on the medical records of 2,143 children across China, 94% were classified as being either asymptomatic, mild or moderate cases.
“This means they may be less likely to have a cough, and so release smaller amounts of virus into the environment,” explains Zoë Hyde, an epidemiologist at the University of Western Australia.
This all suggests that when it comes to the delicate process of working out the best ways to reopen schools en masse while protecting the local community, the biggest need for stringent precautions such as testing, social distancing and masks will be at secondary level.
How can schools be kept safe?
Between April and early June, about 20 countries – from the UK to South Africa – tentatively began to reopen schools. While this experiment had a few failures – China, South Korea and Israel all had to shut some schools again after new outbreaks – it also yielded a number of interesting patterns to learn from ahead of more large-scale openings this autumn.
Different nations have applied different strategies to their schools as a means of keeping the virus at bay, from compulsory daily temperature readings in Vietnam, to random swab testing in Uruguay. Emiliana Vegas, co-director at Brookings Center for Universal Education in Washington, has been monitoring these various approaches. Overall, she says that a combination of keeping class sizes small and asking older children to wear masks and socially distance appears to be the most effective way of keeping schools and communities safe.
The former strategy has been used effectively over the past few months in Finland and Denmark. Large classes have been broken up into smaller pods of 15 to 20 students, who are taught separately and allowed to congregate in the playground, where the open air reduces the likelihood of virus transmission. “Having the pods means that if one person gets infected, you don’t have to quarantine the entire school,” says Vegas. “It also makes contact tracing much easier when cases occur.”
But scientists point out that the most appropriate measures vary from country to country, depending on the amount of virus circulating in communities. Where clusters of new cases are still regularly occurring, stricter social distancing measures may be needed, as well as compulsory masking.
“The stance taken on masking in schools must depend on the magnitude of outbreak,” says Otto Helve, a paediatric infectious disease specialist at the Finnish Institute for Health and Welfare. “In Israel, for example, where masks are compulsory for all students, there is a worse outbreak in society, but the classes in schools are also bigger and the classrooms generally smaller. Also, children spend much more time together in enclosed spaces, such as school buses, compared with Finland, where children tend to walk to school.”
There are, however, concerns about applying strict social distancing and masking policies to younger age groups, particularly given the growing evidence that they are far less likely to spread the virus. Vegas points out that for primary-age children, being able to play with peers is important for their development. And there are worries that masks could lead to behavioural problems, especially in the western world where children are not used to wearing face coverings during seasonal flu outbreaks. “Young children take a lot of cues about how to behave from the facial expressions of adults and others in their class,” says Vegas.
courtesy: The Guardian