While you may think Republicans are the party of death, that's certainly not how they see it.
There are many other incentives here.
Republicans seem to be more optimistic about COVID going away, so that's one immediate difference in outlook. Democrats are more willing to push for restrictions (IE- insisting that people who are vaccinated wear masks.)
Republicans are more likely to believe that parents know better about how to raise their kids than government does, and the whole argument about vaccinating children fits into that. In addition, the science does show that children are at significantly less risk of COVID complications.