No purpose except for actually knowing whether it actually reduces severity.
> What we can observe is that given matched populations the unvaccinated die at a considerably higher rate than the vaccinated. Beware of some bogus "studies" to the opposite--which didn't use matched populations. Those at higher risk are more likely to be vaccinated and a vaccinated high risk individual can easily still be more likely to die than an unvaccinated low risk individual.
The sad reality is that you can't do matched population without a randomized controlled trial. You can't control for confounders you don't understand.
A recent hillarious example is the well-publicized paper that showed a drop of over 90% in Covid-related mortality after the first booster. Other researchers managed to obtain the data and it turned out there was also a similar drop in non Covid related morality. This resulted in the following correspondece, which is well worth reading:
https://www.nejm.org/doi/full/10.1056/NEJMc2306683
A choice quote from the authors of the original paper:
> During the B.1.617.2 (delta) wave in the United States, similar associations were observed between the use of mRNA vaccines and lower mortality not related to Covid-191 and mortality from any cause.
They mean that many of the studies showing a drop in Covid mortality after the mRNA vaccines, also showed a similar drops in non-Covid related mortality. In other words, the vaccinated population were healthier at the outset and the drop was bogus.
You need a proper clinical trial here to make this claim, as the observational data is ridiculously confounded.