[cherdano]

What I meant is the following. If someone gets infected during the study period (vaccinated or not), we may not want to count them among the study population for the remainder of the study. But this means our denominators (for the size of the vaccinated/unvaccinated groups) is changing constantly. If I understood correctly, hazard ratios are the normal way of dealing with this.

Is that correct? I guess it's used more commonly for comparing death rates, as most people can die only once.

[kenberg]

I could have, and ok I should have, looked up just what the effective rate was. Even there it gets a bit confusing. Apparently there is both an effective rating and an efficacy rating, the difference being that efficacy apple when they have more control. If they just look at how the vaccinated fare against the unvaccinated, that might not all be due to the vaccine. I now have had four shots. But I also still wear a mask when I grocery shop and I avoid crowded areas. To really get a handle on effectiveness, it seems you want to compare a group of people who are generally cautions and get the vaccine against a group that re generally cautious and don't get the vaccine. The problem being that the second group might be the empty set.

I acknowledge my laziness in not looking into details, I still haven't. my general point still seems right to me. News reports cite statistics, probably they are real statistics if you go to a serious news source, but exactly what the numbers mean is apt to take some thought.

And, like just about everyone, I don't give it enough thought. It seemed clear Pfizer was good, it seemed clear i should wear a mask and avoid crowds, so that's the plan.

[helene_t]

cherdano, on 2022-May-09, 09:33, said:

What I meant is the following. If someone gets infected during the study period (vaccinated or not), we may not want to count them among the study population for the remainder of the study. But this means our denominators (for the size of the vaccinated/unvaccinated groups) is changing constantly. If I understood correctly, hazard ratios are the normal way of dealing with this.

Is that correct? I guess it's used more commonly for comparing death rates, as most people can die only once.

You are probably right, they might have called it incidence ratios rather than hazard ratios if they didn't remove infected patients. But would they know if someone got infected without showing symptoms?