I am one of the people who has scoffed at the temperature screening and said it is a waste of time, but maybe we are approaching this from the wrong perspective and are too focused on the big numbers. The history of recent infectious disease management has been one of advancement through small steps.

The AC press release contained the following;
Customers travelling on Air Canada flights will be subject to an infra-red temperature check at all airports, the first airline in the Americas to announce such measures system-wide. The non-invasive procedure will complement the existing government-mandated health questionnaire currently completed by all travellers to determine their fitness to fly. Customers who are deemed unfit to travel will be rebooked at no cost but be required to obtain medical clearance prior to travel.
This is in effect an "exit" check.

Let's have a look at one of the recent negative reports that dismisses the usefulness of temperature screening. In January, the London School of Hygiene & Tropical Medicine (LSHTM) released a mathematical model* that indicated that for every 100 infected travellers planning to take a 12 hour flight, only 9 would be detected at entry screening upon arrival. 9% isn't impressive is it? When I look at that number, I say, pfft, big deal. Well, what if it is focused on pax from regions that we know are hot spots or if we play the numbers game? For example, in February YYZ, recorded arrivals of; Transborder 1,034,000 & International 1,386,000. Let's be conservative and say 1% of these pax were infected. A 9% detection rate would be 2,147 pax. Let's be even more conservative and reduce that to 1/10 of 1% of the pax as infected, 9% would still identify 20 or so people. Typically we could expect that more of them would arrive from hotspots, so the distribution of arrivals would be at certain hours and days of the week. It wouldn't be an even spread through the month. 1 infected person can cause alot of harm. Airports provide an easy way to sample a large part of the at risk population.

However, included in the report was this chestnut; The model estimated that 49 passengers would be detected through exit screening before they board, but 42 infected travellers would pass both exit and entry screening undetected. The precise numbers depend on how good screening is at detecting symptoms as well as the time periods between infection and illness.
Keep in mind that this is specific to the pax being infected, and is not a general estimate using total pax numbers. The starting point is going to be a small number of pax. However, my takeaway is that the AC proposal may actually help and that we should not be too harsh.The AC proposal emphasizes exit screening and it is something world governments should have been doing at airports long ago.

There is also a really cool modeling tool that I am sure some people here are going to love. https://cmmid.github.io/visualisatio...ller-screening
link to study here. https://www.eurosurveillance.org/con...0.25.5.2000080

I am not the greatest at math, so if my calculations don't make sense, I am sure I will be corrected. My point is that after some reflection, I think we are not giving AC enough credit for its screening aspect, even if the benefit is unintentional.