Is testing and wearing masks working?

Mass testing and masks were a new introduction when schools reopened this time around, but do they work?

CREDIT: This is an edited version of an article that originally appeared on BBC News

How testing could do more harm than good

The government has introduced mass testing in order to reduce the risk of spread of the virus. Secondary school pupils were offered three tests on their return, and they have been asked to carry these out twice a week at home from now on.

The rapid lateral flow tests provide a quick result, on the spot, unlike the ones that are carried out in official testing centres – known as PCR tests – which are sent off to labs. The rapid tests are less accurate – they may pick up only between half to three-quarters of positive cases – but, given they are being used to spot cases before people develop symptoms, or for those who do not develop symptoms, the government is adamant they have an important role.

The problem is they can result in a false positive, telling people they are infected when they are not. Research suggests this happens one-to-three times for every 1,000 tests carried out.

Assuming most pupils take up the option of the tests, that could result in thousands of pupils, and their close contacts, being asked to isolate unnecessarily. That might be a price worth paying if it was spotting many more positives, but the testing done in schools in recent weeks shows the number testing positive is now at the lower estimate for the false positivity rate.

Birmingham University biostatistician Professor Jon Deeks says, given the low detection rates being seen, it is “absolutely clear” that many of those getting positive test results next week will be receiving false positives.

“Any testing system is a trade-off between benefits and harms,” he says. “My concern is that it will actually cause more harm than good.”

Has masks policy opened a can of worms?

The second key change – and the most controversial – is the recommendation of masks in classes for secondary age schoolchildren; previously, pupils were just expected to wear them in communal areas, like corridors.

Critics say it will harm learning and is unfair to expect children to wear masks for hours on end – but others have argued it is an absolute necessity, and should have been introduced in primary schools too.

The problem is that the benefit of mask-wearing is difficult to quantify. Recent evidence from the government advisory group SAGE acknowledges this, although it says there is evidence that, worn correctly, they will have a “small but significant” impact on transmission by preventing the wearer from spreading the virus if they are unknowingly infected. This is mainly derived from lab experiments, though, and much will depend on how they are used, it says.

It is for this reason some experts say they would have liked to see a proper trial in schools to measure the impact. “We always do this for a medical intervention – there are lots of things that work in the lab but not in the real world,” says Professor Jonathan Ball, a virologist at Nottingham University.

“For some reason, we don’t do this with non-medical interventions. It would be complicated, but this would be the ideal opportunity to do it – to help us decide if they are useful, or make matters worse.”

Without a trial, the fear is it will be difficult for the government to stop the practice. If cases remain low, it could be argued masks have made the difference and, if they creep up, the case could be made they would have gone up more without mask-wearing. The move could, in other words, open a can of worms.

Why rising infection rates may not matter

It is well-established that children are at incredibly low risk from the virus, while research by the Office for National Statistics has shown that teachers are at no higher risk of infection than other, working-age, people.

What role will schools play in the wider spread of the virus remains more open for debate; children, after all, come home and mix with their families. Government advisers say schools have not been a key driver of infections so far; this much can be seen from the impact of the second national lockdown in England, in November, when infection levels fell despite schools being open.

But this was before the new UK variant became dominant. Modelling has suggested that reopening schools now could be enough to drive the R number above one, which would lead to a growing epidemic.

Ministers have already indicated this matters less than it used to because the vaccination programme has begun to break the link between infection rates and serious illness and death – the R number is not one of their tests for slowing the pace of lifting lockdown.

Dr Muge Cevik, an infectious disease expert at the University of St Andrews, says it is impossible to disentangle exactly what impact schools have – although she says all the evidence suggests that the school outbreaks that have happened have mainly been small. “The evidence of harms of closing schools is clear. They should be open as default unless there is very strong evidence that closing them will have a significant impact on hospitalisations and mortality.”