The best thing for society is for me to take the first vaccine I'm offered. But selfishly speaking, wouldn't I personally be a lot better off with the 95% effective Pfizer or Moderna vaccine than the 65% effective Johnson & Johnson shot? Or am I just a jerk? —Vaccine Varlet

This is why we should never share actual clinical trial results with the public. Just today I saw an email claiming that deaths among the unvaccinated group proved that the placebo was killing people, in a sort of Möbius strip of ignorance that I can only describe as almost elegantly stupid.

In any case, don't worry too much. As the immortal Jeff Lebowski didn't quite say: You're not an asshole, Varlet, you're just wrong.

Before I get into the reasons that the percentages you cite aren't what they appear to be, let me cite a more important one: 100%, as in "all three of the vaccines you mention were 100% effective at preventing death or hospitalization due to COVID." After that, frankly, the rest is details.

In any case, the reason those percentages aren't comparable is because the experiments were done at different times, in different geographical areas, on different people.

Your precious Pfizer and Moderna vaccines were tested in the U.S. during the late summer and fall, when COVID cases were at a low ebb—so low that not only did no one in Pfizer's vaccinated group die of COVID, nobody in its placebo group did either.

The Johnson & Johnson shot, meanwhile, was in the field during the winter spike in cases. Its study also included Brazil and South Africa—each home to a new COVID variant—as well as the U.S., and there were a quite respectable five COVID deaths in the placebo group (and none in the vaccinated group, as above).

In fact, if I was a flack for Johnson & Johnson who drank too much on Twitter, I could plausibly boast that my company's shot was the only one battle-tested against the so-called South Africa variant. I might also point that one shot is a lot easier than two, and I might ask, rhetorically, what kind of lame vaccine can't even be stored in a normal refrigerator?

Then I could move on to emasculating insinuations about the other vaccines' low placebo-group body count. Then I'd probably get fired. Anyway, the point is, all vaccines are beautiful in their own way. (Except maybe AstraZeneca.)

Questions? Send them to dr.know@wweek.com.