Children and adolescents are said to be half as likely to contract the coronavirus as adults, a scientific review of studies from around the world suggests.
Researchers found that persons under 20 years of age were 56% less likely to contract Sars-CoV-2, the official name of the coronavirus that causes Covid-19 disease, from an infected person.
But the assessment of global testing and tracking and population studies, led University College London (UCL), said the evidence “remains weak” about how likely children are to transmit the virus to others.
Researchers also concluded that they did not have sufficient data to investigate whether children under 12 years old differed from teens in susceptibility to the virus.
The study’s lead author, Professor Russell Viner of the UCL Great Ormond Street Institute of Child Health, said it was the “first comprehensive study” to assess what is and what is not known about “sensitivity and transmission” in children.
He said, “Our findings show that teens are 56% less likely to contract Covid-19 from infected others.
“Sensitivity is an important part of the infection chain, and this supports the view that children are likely to play a smaller role in transmitting the virus and spreading the pandemic, although much uncertainty remains.
“This new data provides essential evidence to governments around the world to inform their decision-making on whether to reopen schools and reduce or end lock-in measures.”
For the assessment, researchers screened 6,332 studies and identified 18 with useful data.
Nine of these were contact investigations from China, Taiwan, Japan and Australia, eight were population surveys and one was a systematic review of contact investigations in small households.
Researchers found that although children seem to be less likely to get the virus from others, it remains uncertain how likely young people are to transmit it after the infection.
Overall, they believe that their findings imply that children play a smaller role in the transmission of the new coronavirus at the population level, because fewer of them will be infected in the first place.
The researchers emphasized that their non-peer-reviewed research does not provide information about the level at which children can transmit the virus if they are infected.
Prof Viner said the study should not yet be published in a journal, but researchers found it important to share it as part of the public debate.
Researchers acknowledged that their work was limited due to the low number of studies used and their mixed quality.
Prof Viner said on a webinar hosted by the Science Media Center on Friday, and said the studies did not allow researchers to separate the data based on a child’s age.
They also could not see whether children with different ethnic minorities or economic backgrounds were at higher risk.
When asked about the possible reopening of schools in England next month, Prof. Viner said the research was not about this issue, but the data could be used to look at it.
He added, “It is preliminary evidence, but I think the weight of the evidence is clear that children seem less susceptible to SARS-CoV-2.
“We have no data on transferability. We clearly have a state of uncertainty.
“I don’t think it helps to make statements about what is safe and what is not safe as absolute. All security is a measure of security.
“There are safety problems out our front doors, there are safety problems in our car to take our children to school, we can never say anything is safe or unsafe.”
Prof Viner said, “the risk of death or serious infection from Covid-19 is exceptionally low in children”.
He said that having an “effective testing and tracking mechanism is very important to reduce the uncertainty about transmission by children”.
Prof Viner said that cooperation between education and health systems was needed to collect data and monitor infection rates, including testing and tracing in schools.
Chris Bonell, professor of sociology of public health at the London School of Hygiene & Tropical Medicine (LSHTM), told the webinar that measures to reduce the risk of transmission in schools were important, such as using an attendance and absence schedule.
He recognized that teachers would not have time to help evaluate whether measures worked in schools, but suggested using video cameras with appropriate safeguards