Yes of course, sorry, I mean you don’t expose them to the virus as part of the trial, the trial tests the safety of the vaccine. Once back out in the general population, you do then track them to monitor if they get it or not.
That’s not how a typical vaccine trial works. The efficacy of the vaccine is established in a lab. The trial tests whether people have a reaction to the vaccine, it doesn’t establish the efficacy because you don’t expose the participants to the virus in a typical vaccine trial.
There are...