How it works: We know the coronavirus affects different people in different ways. So, ideally, we’d want to know how well each vaccine works in people with the most significant risk factors.

“We may not have a lot of that coming out of these trials. They’re certainly not powered to address these subgroup-specific effects,” Dean said.

“If we don’t have adequate data in the greater-than-65-year-old group, then the greater-than-65-year-old person shouldn’t get this vaccine, which would be a shame because they’re the ones who are most likely to die from this infection,” vaccine expert Paul Offit said in a recent conversation with scientist Eric Topol.

The FDA will be looking for evidence of how well each vaccine works in the overall population, so that’s the question their clinical trials are set up to answer.