The sort of polio vaccine used in rich countries is almost 100% effective after three doses. I did some spot checking of a bunch of vaccines I'd heard of and m

The sort of polio vaccine used in rich countries is almost 100% effective after three doses. I did some spot checking of a bunch of vaccines I'd heard of and most seem to be between 90% and 99% effective so Covid-19 vaccines seem to be in line with expectations. The flu is worse but that's always a guessing game of which strain will be prevalent when they're making the vaccine. I think that's because more doses tend to be more effective and if a single dose doesn't get you there they just give you more doses, like the two doses for the mRNA covid vaccines. Effectiveness here is how many people get sick. You don't know in this circumstance that they're going to get sick until it happens, though maybe you could keep track of everybody's antibody levels compared to what they should be and guess. That would be way more expensive than just giving everybody the same schedule of doses though.