Ramp up test, trace, isolate to avoid second deadlier virus wave

Test, trace, and isolate strategies need to be ramped up across the UK in order to reopen schools in September without risking a second virus wave of double the size, scientists warn.

A UK modeling study published in the Lancet Child and Adolescent Health today found schools could safely reopen as long as there is a high coverage of test-trace-isolate nationally.

Led by researchers at UCL and the London School of Hygiene and Tropical Medicine (LSHTM), the study found testing of between 59% and 87% of symptomatic people was needed.

But testing also needs to be backed by comprehensive national system of test, trace and isolate. Scientists quantified this, saying 68% of contacts needed to be traced, and 75% of individuals with symptomatic infection diagnosed and isolated for schools to reopen full-time (65% if schools reopened part-time). If only 40% of contacts could be traced, the proportion of individuals with symptomatic infection diagnosed and isolated would need to increase to 87% and 75%, full-time and part-time opening respectively.

Professor Chris Bonell of LSHTM, a senior author on the study, said: “Our study should not be used to keep schools shut because of a fear of a second wave but as a loud call to action to improve the infection control measures and test and trace system so we can get children back to school without interrupting their learning again for extended periods of time. This is even more important in the context of opening up other areas of society.”

The modelling assumed that lockdown measures would be gradually eased nationally, alongside schools reopening.

If the levels of test, trace, isolate fall below those benchmarked in the study, the authors predict the R number rising above 1 and a resulting secondary surge of infections 2 to 2.3 times the size of the original COVID-19 wave. Scientists predict the secondary peak would hit in December if schools reopen full-time, and February 2021 if they reopen part-time.

Another study, also published in the same journal today, used real world data from the first COVID-19 wave in New South Wales, Australia. It found low levels of transmission of the virus in schools and nurseries, also suggesting re-opening schools could be safe if backed by comprehensive system of test, trace, isolate. However further research on children’s transmission rates is needed.

LSHTM Professor W John Edmunds said: “Both studies give potential options for keeping schools open and show the clear importance of adequate contact tracing and testing. Macartney and colleagues [referring to the NSW study] suggest that educational settings can remain open provided measures, such as contact tracing, quarantine, and even school closures, are in place to limit spread when cases occur.

“Panovska-Griffiths and colleagues [referring to the UK modelling study] suggest that the safe reopening of schools in the UK could occur if the test, trace, isolate programme is greatly improved. However, many questions remain, including whether there are age-related differences in susceptibility and the likelihood of transmission between children and adolescents.

“We urgently need large-scale research programmes to carefully monitor the impact of schools reopening, as Public Health England’s sKIDs study aims to do. Only in this way can we take the most appropriate measures to mitigate the risks and allow us to reassure parents, pupils and teachers alike that schools are safe to attend.

“There are no quick fixes 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 safely and as quickly as possible.”