As I understand it, the reason we don't have that data about the COVID vaccines is that it's costly to check for it. It's much easier to measure symptomatic cas

As I understand it, the reason we don't have that data about the COVID vaccines is that it's costly to check for it. It's much easier to measure symptomatic cases than it is to regularly test everyone in the study to confirm that they don't have an unsymptomatic case. I believe we do think the vaccines prevent COVID, but we just haven't confirmed that.