The study is tailored to the standards of vaccine approval, of course it is. They need to prove safety and efficacy, so they design a trial which will allow those factors to be measured.
Kind of difficult to prove efficacy if you don't know how many people in your trial were infected with the disease you're trying to vaccinate against though. But do bear in mind as mentioned in other comments this participant was not in the phase 3 trial, and phase 3 is where the immunity given by a vaccine is tested. Phase 1 and phase 2 are much more constrained studies intended to determine if it's safe to give the vaccine to enough people to evaluate immunity.
Since this is would presumably be testing for efficacy I guess they would have a number of pre-determined "interim analysis" points in the study when X count of people report becoming positive for the coronavirus. If the proportion infected in the treatment vs control is too high (i.e. lots of vaccinated ppl got sick) they will stop the trial and consider the vaccine a failure. If too few get it, they might stop the trial and immediately move to a Phase III study to confirm their result - that is they accelerate the trial to get the treatment out quicker.
I am unsure if they will have some lower bound for acceleration for this vaccine, since the downsides might not be apparent for a long time.
Kind of difficult to prove efficacy if you don't know how many people in your trial were infected with the disease you're trying to vaccinate against though. But do bear in mind as mentioned in other comments this participant was not in the phase 3 trial, and phase 3 is where the immunity given by a vaccine is tested. Phase 1 and phase 2 are much more constrained studies intended to determine if it's safe to give the vaccine to enough people to evaluate immunity.