Has it actually been demonstrated that childhood illnesses confer lifelong immunity? Or immunity which lasts significantly longer than a vaccine.
If I understand it the argument here isn't that herd immunity doesn't work to stop diseases circulating in the population. I think these discussions accept that as long as a high enough fraction of the population are immune to a disease the overall amount of it circulating will drop - to the significant benefit of those who are not immune - for whatever reason, since they will be much less likely to encounter the disease and get sick.
The problem seems to be with the idea that vaccinations don't create immunity which lasts as long as actually getting the disease. So that comes back to my first point. I'd like to see proof of that statement. I can see that it could make sense. Since vaccines use weakened (or even dead) versions of the disease agent I could perhaps understand that the immune system would not have such a vigouros reponse (doesn't make you sick for one thing) and so not "remember" the way to fight the disease for as long. But I have no real science to back up that idea.
Also even if this were true I'd have to think about cost/benefit in terms of vaccines give you immunity which doesn't last as long (cost), but you don't get the actual disease (benefit), before this could convince me that vaccination programmes were worthless.
Interesting idea though.
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