It would be interesting to see this calculation using the second derivative rather than the first.
Vaccination rate (vaccines given per day) continues to increase in the data I've seen so it does not make sense to extrapolate using only the rate from the last 2 weeks.
I suspect that's because there was a deadline to get the most vulnerable groups done by mid February. I expect something similar will happen after we pass the next deadline.
Even people previously infected are being offered the vaccine, but there are currently studies as to whether those previously infected may only need 1 dose so that the second dose may be used on someone else.
Herd immunity kicks in somewhere less than 100% vaccinated (should start seeing some numbers coming out of Israel in the next few months). A sizeable percentage of the population has had Covid already and therefore has some level of natural immunity (not full, but better than nothing). Furthermore, kids have been shown to spread it less (and we're not vaccinating them currently, reducing the population 20-25%). So all that said, 100/100 is a pretty good short-term target. Yeah - we can and should do better in the long term, but ~100 should get us into a sustained decline (but not eradication - to your point about requiring more long term).
> Herd immunity kicks in somewhere less than 100% vaccinated
Yes, but 1 adult "100% vaccinated" takes 2 doses of any of the current vaccines.
if 75% of the population of a country are "adults who can be vaccinated", and the rest are e.g. under 16, or the few adults will have medical issues that prevent vaccination; then you're shooting for 1.5 vaccines per person, i.e. 150%.
