Covid testing and contact tracing key to reopening schools safely, two new studies suggest


British researchers have found that schools can safely reopen as long as enough contact tracing was in place. Contact tracing strategies involve enough testing to find cases, isolate those people, and then find and quarantine their contacts. And an Australian team found that even though schools remained open in NSW between late January and early April, children and teachers did not significantly contribute to the spread of Covid-19 – because good contact tracing and monitoring strategies were in place.

The UK study is using a model to estimate the amount of testing and contact tracing that would be needed to prevent a second wave of Covid-19 after schools reopened in September. The study suggests that, depending on the scenario, between 59% and 87% of symptomatic people in the community would need to be tested at some point during their infection, their contacts should be traced and people with the disease should. be isolated. in order to avoid an epidemic rebound.

“Our study suggests that it would be possible to avoid a secondary epidemic wave in the UK if enough people with symptomatic infection can be diagnosed and their contacts traced and effectively isolated”, Jasmina Panovska-Griffiths, senior researcher and master of lectures in mathematical modeling at University College London, which led the UK study, told CNN in an email.

“However, without sufficient coverage of a test-trace-isolate strategy, the UK risks a serious second epidemic peak in December or February,” she added in a statement.

“The document emphasizes the importance of testing”

Panovska-Griffiths and his colleagues ran a variety of scenarios to see how much contact tracing should be done in order for schools to reopen safely. One scenario represented schools reopening full time and the other schools reopening part time, with half of the students attending school on alternate weeks.

Overall, the model predicted that with the reopening of full-time or part-time schools, along with the relaxation of other social distancing measures, a second wave of the UK epidemic could be averted. whether enough people with symptoms of Covid-19 could be diagnosed and their contacts. traced and effectively isolated.

“In summary, our results suggest that reopening schools may be part of the next step in the gradual easing of the lockdown if combined with a high coverage – trace – isolate testing strategy,” the researchers wrote in the study.

They added that their results were consistent under the two hypotheses that children transmit coronavirus in the same way to adults or that infectivity in children is 50% compared to those 20 and older.

“The paper highlights the importance of testing a high proportion of symptomatic COVID-19 cases and tracing a large portion of their contacts, but as the authors note, the analysis examines a very optimistic scenario on speed and performance. testing – it assumes that the test is 100% accurate, that the results are received within one day and that everyone isolates themselves for two weeks, ”Adam Kucharski, associate professor of infectious disease epidemiology at the London School of Hygiene & Tropical Medicine, which was not involved in the new study, said in a written statement.

Rapid tests needed for most effective coronavirus contact tracing, research finds

“In reality, there will be a trade-off between speed and efficiency – even if a high proportion of people with COVID-19 are tested, it will not stop transmission if test results take too long or if contacts are infected. are not traced until they become contagious, ”Kucharski said. “To have maximum impact, testing and traceability will need to identify and isolate a large proportion of infected cases and their contacts, but also do so quickly enough to anticipate the epidemic.

The study had other limitations, including the fact that the model results are only estimates that predict what might be possible under various scenarios – and therefore the predictions are not final for the future.

Further research is also needed to determine if the model would make similar predictions for the United States and other countries around the world.

Globally, more than 1.5 billion students – or 90% of the world’s students – have been affected by temporary school and university closures this year due to the pandemic, according to the United Nations United Nations for Education, Science and Culture.

“Both studies offer potential options for keeping schools open”

For the other study, also published in The Lancet Child & Adolescent Health, Australian researchers found that although 27 children or staff from 25 schools and daycares attended Covid-19 while infected, only 18 others were subsequently infected.

Through contact tracing, 1,448 close contacts were identified and called. They were told to get tested if they had any symptoms. Overall, 633 were tested. But only 18 of them tested positive – an attack rate of 1.2%.

Nine of the 10 parameters had no secondary propagation.

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It is possible that some cases were missed, the researchers said, but they said others could use their studies to decide whether and how to reopen schools.

“Both studies offer potential options for keeping schools open and clearly show the importance of adequate contact tracing and screening,” wrote British epidemiologist John Edmunds, of the London School of Hygiene and Tropical. Medicine, in an editorial accompanying the new studies in The Lancet Child & Adolescent Health on Monday.

“However, many questions remain, including whether there are age-related differences in susceptibility and likelihood of transmission between children and adolescents. We urgently need large-scale research programs to closely monitor the impact of reopening schools, ”Edmunds wrote.

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


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