What specific endpoint(s) were used in determining the efficacy of the Pfizer and Moderna Covid-19 vaccines during the FDA trials? I have been searching over various articles and pages from the CDC and elsewhere, but I haven't yet found a specific description of what endpoint(s) were used to define efficacy in the FDA Covid-19 vaccine trials for the Pfizer or Moderna vaccines. There are multiple articles suggesting reasonable primary and secondary endpoints to determine efficacy but nothing showing what they actually used.
Some possible endpoints:

*

*percentage who contracted Covid-19

*percentage who developed no, mild, or severe symptoms

*percentage hospitalized

*percentage who died

*transmissibility

*viral load a certain number of days after infection

If this info is available I'd like to know what combination of the above endpoints was used to get the 90-somehing percent efficacy results, and if possible how the math would have been done (ie. are multiple endpoints combined in some weighted fashion e.g. where hospitalization/death are primary endpoints but then secondary endpoint of viral-load is factored in).
In short, when we say a vaccine was found to be N% efficacious, what does that specifically mean?

As mentioned, a vaccine’s efficacy is measured in a controlled clinical trial and is based on how many people who got vaccinated developed the ‘outcome of interest’ (usually disease) compared with how many people who got the placebo (dummy vaccine) developed the same outcome. It’s important to note that the various clinical trials relating to vaccines is merely a rough probabilistic measurement of efficacy – even in a well defined study with control groups, there are numerous independent biological variables that cannot be measured quantifiably.
