The government has just one month to significantly boost its test-and-trace systems or risk a “second wave” of coronavirus after schools reopen, researchers have warned.
Against a backdrop of rising Covid infection rates in some areas and the introduction of local restrictions, the government has reiterated its determination to reopen schools in England to all pupils in all year groups in September.
But researchers who modelled a range of scenarios for the reopening of schools as part of a wider easing of lockdown said there would need to be a rapid improvement to the test-trace-isolate system to avoid a resurgence of the disease.
Labour and teaching unions, responding to the latest research, called for a more robust test-and-trace system. The shadow education secretary, Kate Green, said schools were making great efforts to welcome pupils back safely, but couldn’t do it on their own. “The government can’t walk away from its responsibilities,” she said. “Ministers must rapidly improve the test-and-trace system before pupils go back to class in September.”
Paul Whiteman, the general secretary of the NAHT school leaders’ union, said the research showed how many factors there were to preventing a worsening Covid-19 outbreak, most of which were entirely outside a school’s control.
“The success of September’s return to school rests as much on what happens outside the school gates as within. The government needs to ensure that everyone knows what actions they should be taking to keep everyone safe – we’re all going to need to work together to be successful.”
The closure of schools to most pupils during lockdown and only partial reopening has raised concern among experts about the impact on children’s mental health as well as their education. But the planned reopening of all schools in England in September has also been questioned, amid fears it may not be safe for the move to go ahead.
“As countries are easing lockdown measures it is important to assess the impact of different lockdown exit strategies including whether and how to reopen schools as the first step of reopening society,” said Prof Chris Bonell, the co-author of the new research from the London School of Hygiene and Tropical Medicine.
“We aim to estimate the level of testing needed to avert a second wave in different scenarios of coverage of [test, trace and isolate programmes] and students returning to school full-time or part-time.”
Writing in The Lancet Child and Adolescent Health, the team report how they built their models based on UK data from the epidemic along with a range of assumptions, including that under-20s transmit coronavirus equally to older age groups, that 30% of onward-transmitted infections are asymptomatic and that any reopening of schools would occur alongside other changes in society – including as few as 30% of adults working from home and a wider mixing in the community.
The results reveal that should schools fully reopen in September, alongside a relaxation of other measures, and 68% of contacts of infected people can be reached, but only 18% of symptomatic adults are tested and isolated, the UK could face a second wave of infections up to 2.3 times the size of the recent epidemic, with a peak in December.
“This is a scenario we have modelled, not a prediction of what is going to happen,” said Bonell, with the team adding that any second wave is not necessarily about transmission in schools but an increase in broader society.
The team say a second wave could be avoided in this scenario if 75% of people with symptoms were tested and isolated, while if half of pupils attend school each week on an alternating rota system, this drops to 65%, and to 61% if there is a full reopening of schools but those under 20 are half as infectious as older ages.
The team also looked at a more pessimistic scenario. If only 40% of contacts can be reached and infectiousness does not vary with age, 87% of symptomatic people would need to be tested and isolated should schools fully reopen alongside wider relaxations.
“Currently TTI is not achieving the levels that we modelled,” said Bonell. At present the team say English data suggests about 50% of contacts of symptomatic Covid-positive cases are reached, while the percentage of symptomatic cases tested, they say, appears to be about 50%.
The latest data from the test-and-trace system in England reveals just over 4,000 new symptomatic cases are diagnosed every week. However, the Office for National Statistics suggests there are currently about 4,200 new cases in England every day.
Another study published in the same journal adds weight to the view that the transmission risk in schools and nurseries is low, at least when a robust TTI system is in place.
The study, based on TTI data, found that across 7,700 schools and nurseries in New South Wales, Australia, 27 children or teachers turned up when infectious at 25 facilities between the end of January and early April 2020. However, only an additional 18 people later became infected. While there was one large set of secondary infections at one nursery, there were no secondary infections in nine of the 10 of the nurseries and in 12 of the 15 schools.