As far as I know, and again this is not my area of expertise, there is something called an immigrant health exam, which people get before they migrate here. People who arrive through other means get an immigrant health exam once they put in their refugee claim. If you're a visitor who comes for less than six months, you don't have an immigrant health exam.
The idea of immigration being a control on infectious disease probably is not the way the current scenario is laid out. It perhaps wouldn't even be very effective. If so, what we would be doing is targeting the 500 million people who are coming through Canada for short visits, because I think the risk of infectious disease extends across the globe, and—