Safe events

Can rapid testing make your events safer? Yes. Are they guaranteed to do so? No.

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.)


I have been getting a lot of queries lately from people holding in-person events in the Fall. From weddings to smaller conferences. Everyone attending is required to be vaccinated. I am less clear about whether other people, hotel workers or catering staff, are vaccinated but let’s presume that they are for the purposes here. The question is: how can they use rapid antigen tests to make things safer? Of course, what they are really asking is: how can I use these tests to avoid making the event a super-spreading event?

For starters, it is important to accept that there is no such thing as no risk. A few months back, an event tried a testing blitz but it didn’t work. That was pre-vaccine but it should be a cautionary tale.

Nonetheless, testing tells you things. First of all, if every one has taken a rapid test before arriving at the conference, then you have high confidence that someone hasn’t arrived at the conference being infectious (then and there) and likely not infected before stepping on a place to get there. So, if you can, make sure everyone has a test before getting there.

Second, that isn’t perfect. They may contract the virus a day or two before that rapid test was taken or, travelling to the conference. If the conference is a one-day affair, the chances that they spread to people at the conference remains low. If it is multi-day, however, they may become infectious during the conference which is what you are trying to avoid.

How do you manage that risk? The answer is to test again. The idea here is that you may catch people on the upswing in terms of their viral load increasing and prevent them from spreading to others. The obvious time then is to do this prior to breakfast on the next day.

And that suggests a strategy. Test people just before breakfast each day of the event. This has the advantage is that you can measure and monitor compliance more easily than if you do the testing in a haphazard way.

Now let’s turn to the risks. Public health people hate this use of rapid tests. They argue that it provides a sense of complacency and so people won’t socially distance or wear masks. To an economist, this is of course the point. We want people to be less anxious and enjoy the conference in a normal way and so the tests are a way to do that.

How do we reconcile those two views? The issue is what the default situation is. If in the absence of tests, you would be having the conference but with social distancing and masks, then the public health people may have a point. It is possible that testing could reduce compliance with those things. But on the other hand, if, in the absence of tests, your plan is to have a normal event, then testing cannot reduce compliance as there is no expectation of it. It can only reduce risk.

I have my own opinion on the matter of compliance but it is just an opinion and it is really hard to judge. People will know their own people better. So I just put this there and you can work out if you are increasing risk too much or lowering it.

The second risk is sociological. The problem with testing is that if someone tests positive, then what? I can imagine that organisers don’t want to deal with that situation. But the point I need to stress is that you need to have a plan for that. What happens? Do you shut down the event? Do you revert to distancing? What do you do with a person who is positive? And in these events everyone will know who it is and so how do you manage that? Again, there are many factors here and I don’t want to specify what you should do. It depends on too much. My point is that you should have a plan upfront and explained it to everyone.

This is also because there is another sociological risk. No one wants to be the person seen to close down an event. That means there is a risk in self-assessment and reporting. If you can use some means by which tests can be administered easily but in a way that positive reports are automatically reported or safe to report. The biggest challenge here is the testing before arrival suggestion. You may need to test upon arrival as well if you aren’t confident that will work.

In summary, having everyone vaccinated is the big step. If prevalence is low, testing is icing on the cake. If prevalence is high, then testing can help reduce risk significantly. There are just no guarantees and so you need to make a clear judgment as to your options.