Virus test, tracing essential contacts for schools to reopen safely, studies find


TORONTO – Effective contact tracing and viral testing are essential for the safe reopening of schools during the COVID-19 pandemic, two new studies show. The studies, published Monday in The Lancet Child & Adolescent Health, found that levels of transmission of the coronavirus in schools are low when public health measures are in place.

The first study used modeling data to analyze whether a second wave of infections could be prevented in the UK if security measures were stepped up in schools when they reopened. The second study analyzed real-world data from the first wave of COVID-19 infections in New South Wales, Australia, to understand the transmission of the virus in schools and nurseries.

Both studies concluded that schools can operate safely if effective virus control measures are in place.

In a linked commentary discussing the studies, W. John Edmunds, a professor at the London School of Hygiene and Tropical Medicine, said the two studies offered other countries potential options on how to keep schools open in the midst of the pandemic.

However, without knowing the differences in sensitivity related to age or how COVID-19 is transmitted between children, he said more research is still needed.

“We urgently need large-scale research programs to carefully monitor the impact of the reopening of schools… Only then can we take the most appropriate measures to mitigate the risks and enable us to reassure parents, students and teachers that schools are attending, ”Edmunds said.

Edmunds added that both studies underscore the “clear importance of proper contact tracing and tracing” needed to ensure that schools remain a safe place for students and staff.

“There is no quick fix to this terrible pandemic. However, it is becoming increasingly clear that governments around the world must find solutions that allow children and young adults to return to full-time education as quickly and safely as possible, ”Edmunds told me. said.


The first study, led by researchers at University College London and the London School of Hygiene and Tropical Medicine (LSHTM), found that a second wave of infections in the UK could be prevented with increased levels of testing, contact tracing and isolation in schools. reopen.

Assuming that 68% of contacts with the virus can be traced, the researchers reported that 75% of children with symptomatic infection should be diagnosed and isolated if schools return to full time in September. The study found that 65% of those infected would have to be diagnosed and isolated if schools resumed part-time.

If only 40% of contacts could be traced, those numbers would increase to 87% and 75% respectively, according to the study.

If diagnostic and contact tracing levels were to fall below these numbers across the UK, the study found that reopening schools combined with the gradual easing of lockdowns would likely result in a second wave of ‘roughly double the size of the original COVID-19. wave.

Modeling data from the study suggests that a high school wave could peak in December 2020 if schools are open full-time and in February 2021 if students return part-time.

Dr Jasmina Panovska-Griffiths, who led the study, said in a press release that it is possible for schools to open safely amid the pandemic, alongside other plans for economic reopening . However, she warned that local governments must ensure that screening, testing and isolation capacity is increased before schools do so.

“… The reopening of the school probably goes hand in hand with more adults returning to work and other relaxed measures in society. Therefore, our results reflect a wider loosening of the lockdown, rather than the effects of transmission within schools exclusively, suggesting a test – trace – isolate offers a feasible alternative to intermittent lockdown and school closures to control the spread of COVID-19, ”Panovska-Griffiths said in the statement.

The study assumed that children were as contagious as adults, but since the level of infectivity in children was inconclusive, the researchers also reexamined the model reporting that children were 50% as contagious as adults. Both tests gave the same results.

While the rates of asymptomatic transmission of COVID-19 are unclear, the study assumes that asymptomatic infections account for 30% of infections transmitted.

Despite warnings of a second wave, one of the study’s lead authors Chris Bonell said schools should not remain closed.

“Our study should not be used to close schools for fear of a second wave, but as a call to action to improve infection control measures and the testing and traceability system so that we can bring back the children in school without interrupting their learning again. for long periods of time, ”Bonell said in the press release.

“It’s even more important in the context of opening up other areas of society. ”

While COVID-19 can still pose a risk to children, researchers noted that keeping schools closed for long periods of time can have negative effects on children, including their physical health and well-being. mental, and can also increase inequalities.

The authors acknowledged that there were some limitations to the study. Although they modeled scenarios to look like the UK, some of the assumptions are based on data from different contexts.

The researchers also noted that the study does not take into account the behavior of young people who are out of school.


The second study, led by the National Center for Immunization Research and Surveillance and the New South Wales Department of Health, tracked the spread of COVID-19 in 25 schools and nurseries across Australia from January to April.

The study found that the risk of children and staff transmitting the novel coronavirus in these educational settings was “very low” when contact tracing and other control measures are in place.

The study reported that 27 people – 12 children and 15 teachers – attended school while infected. These infections occurred in 15 schools and 10 nurseries, all of which were temporarily closed for deep cleaning after an infection was reported.

Researchers interviewed all infected people or their guardians at the time of diagnosis to track their school attendance as well as any contact with other people during the time they were contagious. Close contacts were monitored through regular phone calls and were asked to be quarantined for 14 days. If they started showing symptoms, they were asked to take a test.

Of the 1,448 close contacts identified, the study reported that only 18 additional people in three schools and a nursery were subsequently infected.

The outbreak in the nursery was one of the largest, involving transmission from one adult to six adults and seven children. The study suggests that transmission came from staff rather than children and that a number of children were likely asymptomatic.

However, the study noted that this outbreak occurred at the start of the pandemic when screening criteria had not yet been broadened.

Unlike many other countries, Australia kept schools open when the COVID-19 pandemic hit with guidelines in place for physical distancing and hygiene.

The researchers found that these improved safety measures, in addition to effective contact testing strategies, suggest that schools and nurseries do not pose a high risk of further transmission of the virus.

There were some limitations to the study, the most notable being that the majority of close contacts were tested after developing symptoms. The researchers said some asymptomatic or milder cases may have been missed.

Additionally, children in New South Wales were encouraged by government and health officials to stay home and participate in home learning during the last weeks of March. Although schools have remained open, research has shown a drop in school attendance from 90% to around 5%.

Professor Kristine Macartney, director of the National Center for Immunization Research and Surveillance, said that while the study adds valuable data on the transmission of COVID-19 in schools, its findings must be viewed in the context of the global epidemic in New South Wales.

“Higher transmission rates may occur in areas with higher infection levels and where contact tracing and public health measures were not as rigorous as in Australia, where borders have been closed and quarantine measures have been strongly enforced, ”Macartney said in a press. Release.

Of a total of 1.8 million children in NSW, only 98 children were infected between January and April, or 3.2% of the country’s total COVID-19 infections.

“Our results are the most comprehensive data we have to date on the transmission of SARS-CoV-2 in schools and early childhood education settings,” Macartney said.


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