Excess Death Rates for Republicans and Democrats During the Covid-19 Pandemic [pdf]

This topic could be potentially interesting to study, but this particular study is a bit weak, as it makes no effort to control for any other variable which might correlate with party affiliation.

They used a dataset of people in Ohio who voted in 2018 and in Florida who were registered and declared a party in 2017.

They simply compared the death rates of these two groups. They did not attempt to account for age, location, access to quality healthcare or wealth.

In both states -- but even moreso in Florida than Ohio -- party affiliation is heavily correlated with wealth. It is also correlated with age and with the population density of the city/town (which itself is linked to healthcare access)

On the other hand, the fact that the mortality rates only diverged after vaccines became available is pretty strongly suggestive of a casual link involving the vaccines -- but this paper doesn't explore the issue adequately to really change our understanding of the situation.