Rapid screening in schools

A new study shows that it works to keep schools open

Welcome to Plugging the Gap (my email newsletter about Covid-19 and its economics). In case you don’t know me, I’m an economist and professor at the University of Toronto. I have written lots of books including, most recently, on Covid-19. You can follow me on Twitter (@joshgans) or subscribe to this email newsletter here. (I am also part of the CDL Rapid Screening Consortium. The views expressed here are my own and should not be taken as representing organisations I work for.)


Testing for Covid-19 is getting a resurgence of interest with the rise of the Delta variant. Interestingly, it is getting paired with vaccination credentials for many workplaces — that is, you have to be vaccinated or have a negative test to go to work. It is a good way of getting around concerns that vaccines are being mandated with derisking people coming to work.

Of course, for everything else, schools are one of the places where vaccines have been mandated in the past. But with Covid-19 vaccines still not having full approval and not being approved for use by under 12s, doing the same for schools is going to be a problem.

Last week this notion taxed me as I read the Ontario Science Table’s (the Ontario government’s scientific advisory body) report on recommendations for schools. Apart from better ventilation and advocating vaccines for those who could get them, it seemed pretty similar to past guidelines. What cheesed me off, however, were its testing recommendations:

They recommended testing only for symptomatic children or those who had a known exposure. In other words, nothing different from before. What’s worse they did not recommend rapid antigen tests. Why? “Laboratory-based molecular tests are preferred as they are more sensitive than current point-of-care rapid molecular or antigen tests.” This, however, is just plain wrong. The science is clear — as readers of this newsletter would know (and the papers here show) —  rapid antigen tests catch as many infectious cases as PCR tests. Use them regularly and you break chains of transmission so that cases don’t lead to outbreaks that shut schools down.

In reaction to this, I wrote an opinion piece in The Toronto Star, decrying the likely continued disruptions for our schools in the Fall and beyond.

The Ontario Science Table’s approach is to ignore this. They want to only test when we see symptoms or exposure. Their plan is to find out about infections precisely when it is already too late. This is a recipe for rolling school shutdowns, anxiety and failing our children. Workplaces aren’t standing for that uncertainty. Instead, we need to follow the overwhelming science and use every tool we have to get ahead of this and prevent disruption.

This conclusion was based on our experience with rapid antigen screening in workplaces. But a new paper has just appeared that shows this applies to schools exactly on the dimension I was focussed on — avoiding disruptions.

The new study documents an extensive randomised control trial of regular rapid antigen testing in schools in the UK. The trial compared isolation of known contacts to a Covid-19 case for 10 days to daily antigen testing of known contacts but no isolation. Here was its conclusion:

Overall, this study shows that in secondary school and college of further education students and staff infection of following contact with a COVID-19 case at school occurs in less than 2%. There was no evidence that switching from isolation at home to daily contact testing, at least in the settings of the schools studied, increased rates of symptomatic COVID in students and staff. Daily contact testing is a safe alternative to home isolation following school-based exposures and should be considered an alternative to routine isolation of close contacts following school-based exposures.

So there was no change in cases but the schools with testing lost 40% fewer school days and 61% fewer staff-related Covid absences compared to the mandatory isolation schools. This was on a test that conventional standards based on infection would assess at 53% sensitivity.

This is directly counter to the Ontario Science Table’s conclusions on rapid testing. Instead, being able to conduct daily testing is equally protective as sending contacts home but with the considerable upside of keeping the school open for most kids. Not to use every single instrument in our arsenal to keep schools open is surely negligence.

QUICK UPDATE: Denmark recommends regular testing for school kids.