As a layperson I read “prevent” to mean a 100% reduction. Not sure if there’s a slightly different interpretation than that but I’d presume that’s what they mean?
"We all expect an effective vaccine to prevent serious illness if infected. Three of the vaccine protocols—Moderna, Pfizer, and AstraZeneca—do not require that their vaccine prevent serious disease only that they prevent moderate symptoms which may be as mild as cough, or headache."
"Prevention of infection is not a criterion for success for any of these vaccines. In fact, their endpoints all require confirmed infections and all those they will include in the analysis for success, the only difference being the severity of symptoms between the vaccinated and unvaccinated."
>the only difference being the severity of symptoms between the vaccinated and unvaccinated
seems kind of wrong to me. The main difference they are hoping for is the number of cases of illness between the unvaccinated and vaccinated. If you get 100 cases in the unvaccinated group and 1 in the vaccinated it doesn't really matter if the symptoms are a bit better or worse.
