I’m curious if someone more knowledgeable can help me understand how to think about a vaccine that is 80% effective. Is the idea that each person will have a high chance of being essentially immune, and a low chance of having minimal protection? Alternatively, does it offer approximately 80% protection to everyone, the way that masks and social distancing would?

If it’s the latter, it seems like risk compensation could largely undo the effects of an 80% effective vaccine. If I see my family once a week without a mask, and I start going back to the gym, I could easily increase my risk by a factor of 4-5x.

I have one correction on the obesity/overweight numbers, unless I misunderstood the claim being made. In most contexts, including the NCHS numbers cited above, the cutoff for overweight is a BMI of 25, not 30. The cutoff for the vaccine is a BMI of 30, so only ~40% of people qualify, not ~70%.