Tits week of coronavirus testing for students is being rolled out to UK universities. Some institutions already falsely claim that if your test is negative, you will know it is safe to go home. The question is very important to many families, who do not want their children to be stranded as they isolate themselves at university on Christmas, but are also concerned that they are bringing the coronavirus back to the home. home to elderly or vulnerable relatives.
In my work as a professor of population health, I help national governments and policy makers decide whether to run screening programs like those undertaken in universities. Here’s what we do and don’t know about university screening.
A preliminary assessment from Public Health England (PHE) found that the new lateral flow test to be used by universities – providing a result within 30 minutes – had already missed coronavirus cases in a quarter to half of people he tested, giving a negative reading. It’s not just a problem with which particular manufacturer the government chose: the fastest lateral flow type coronavirus tests appear to be missed by many people with coronavirus.
Many students who are recently infected (in the few days before the test) will also be missed: indeed, the coronavirus only becomes detectable a few days after infection. Thus, students who test negative on two tests within days of each other, and self-isolate in between, have the lowest risk of having coronavirus, but because the test misses cases, they may still be infected. Many universities do not advocate self-isolation between tests, so many students infected between the two tests will also be missed.
The existing test and trace program should detect people with symptoms and their contacts. The idea behind rapid university testing is to find students who have coronavirus, but have no symptoms (likely about one in five people infected), so they can self-isolate instead of bringing back the infection at home. For this to work you need two things. First, to accurately detect the coronavirus in students without symptoms. The instructions for using the lateral flow test actually say that it is for people with symptoms – not students without symptoms, for whom it is primarily used here. Second, for the process to work, we need students and their contacts to self-isolate if a coronavirus is detected. We don’t know if they will, but evidence from testing and tracing suggests that many people don’t. So, in the end, university testing may not reduce transmission as much as hoped.
The problem with screening programs is that they often don’t go as planned. There are obvious ways the university screening program could actually increase the spread of the coronavirus. The real danger is that students mistakenly believe that a negative test means they don’t have coronavirus. It would be hard to blame students for such a misunderstanding when Health Minister Lord Bethell announced that evaluations “are already showing that lateral flow testing can be the reliable and highly sensitive technology we need” , and Health Secretary Matt Hancock said he “did not recognize” PHE figures showing cases missing on the test.
Due to the limitations of this rapid test, some students will go straight home after a negative result and either be contagious immediately or become contagious within days. This would happen whether they were tested or not. The problem arises if they mistakenly believe that they are not contagious because they tested negative and they visit an elderly or vulnerable parent under that misconception. There are other potential unintended consequences: Some students, for example, may misinterpret a negative test result as a free party pass, which could also increase transmission.
There’s not a lot of evidence as to whether university screening will do more good than harm, or whether it will reduce or increase infections overall. We don’t yet know how many students will take the tests and how they will react to positive or negative results, among other things.
In a pandemic, decision-making is more urgent and there is little time to collect research data. However, in the UK we have fantastic researchers, dedicated funding streams, and organized systems to put that evidence together very quickly. We don’t deploy a vaccine until we know whether it is safe and effective: we are waiting for evidence from randomized trials. However, we seem to be diving headlong into mass screening. In the research arena, we’ve looked at many other screening programs that seem to make good sense – but when we do a randomized trial, it often turns out that they do the exact opposite of what was intended.
Another lesson learned from decades of running successful screening programs in the UK is the importance of honesty. Authorities need to be honest with people about the good and bad aspects of testing and let them make their own informed choices about whether or not to participate. Families have grown accustomed to balancing the risks this year: we should tell them openly that these tests can detect some asymptomatic cases, but they also miss some, and trust people to make wise choices for their own families.
Such an approach will help avoid the worst possible outcome of screening students for the coronavirus: that returning young people end up infecting elderly or vulnerable parents based on a misunderstanding of what negative results mean. Not only would this result in a completely preventable tragedy for families, but people could also lose faith in the government on the next initiative – the rollout of critically important vaccines.
• Dr Sian Taylor-Phillips is Professor of Population Health at the University of Warwick, specializing in the evaluation of population screening programs