Well, if I had to guess, it's probably both. In statistics, this is called "confounding".
So if you can't run some sort of double blind controlled experiment, one easy way is to look at places in the world where vaccines were applied but a change in sanitation either stayed the same or went down.
One major case like this (just from the top of my head) was the campaign to eradicate smallpox from 1958-1978. During that time a lot of sanitation in especially rural areas in the 3rd world declined due to political instability, but vaccination led to eradication.
Now that is a reasonable argument which I agree with. Quite a bit different from saying that vaccines may not be responsible for the major drops in a virus’s prevalence in parts of the world.
However when you understand that there are other plausible explanations for why a virus became less deadly, then it also puts us into a position to question what effects different vaccines have had, and which were effective. Which I think was the main point of this post.
Well, if I had to guess, it's probably both. In statistics, this is called "confounding".
So if you can't run some sort of double blind controlled experiment, one easy way is to look at places in the world where vaccines were applied but a change in sanitation either stayed the same or went down.
One major case like this (just from the top of my head) was the campaign to eradicate smallpox from 1958-1978. During that time a lot of sanitation in especially rural areas in the 3rd world declined due to political instability, but vaccination led to eradication.
https://en.wikipedia.org/wiki/Smallpox#/media/File:Decade-in-which-smallpox-ceased-to-be-endemic-by-country.svg
Now that is a reasonable argument which I agree with. Quite a bit different from saying that vaccines may not be responsible for the major drops in a virus’s prevalence in parts of the world.
However when you understand that there are other plausible explanations for why a virus became less deadly, then it also puts us into a position to question what effects different vaccines have had, and which were effective. Which I think was the main point of this post.