You understand what vaccination is right?
"natural immunity built up from many in a population contracting the disease"
Vaccination is purposely developing immunity in people by giving them a damaged or weak version of the disease. Their body than creates the necessary antibodies to fight off the real disease should they every encounter it.
Herd immunity is simply showing that with enough people actually immune, you'll protect a small segment that is not vaccinated. However, if that segment becomes too large, the disease will spread.
Think of it like someone wanting to paintball you. We've given some people shields. If enough people have shields, you will never get hit by a paintball or the splatter of a paintball. If too few people have shields, you will almost certainly get hit by paint.
Vaccine-induced herd immunity is (mostly) a myth. There's lots of holes in the 'herd immunity through vaccines' theory, a glaringly obvious one is: Most Vacc only last from 2 - 10 years. Therefore IF the particular vaccine was conferring herd immunity to a particular age group, then the herd immunity would decrease over a few years to levels WAAAAAY lower than that supposedly necessary to stop an outbreak of the disease.
Most adults walking around (i.e most of the population) haven't been vaccinated in many years & therefore wouldn't be immune to all those 'deadly' illnesses like: measles, mumps, rubella, Diptheria, Chicken pox (!!) etc etc. There's therefore NO herd immunity effect here, but the people aren't dropping down dead everywhere.
Herd immunity is a myth propigated to try & sell more vaccines to more people more frequently.
Here's a nice quote: "If we listen to present-day wisdom, we are all at risk of resurgent massive epidemics should the vaccination rate fall below 95%. Yet, we have all lived for at least 30 to 40 years with 50% or less of the population having vaccine protection. That is, herd immunity has not existed in this country for many decades and no resurgent epidemics have occurred. Vaccine-induced herd immunity is a lie used to frighten doctors, public-health officials, other medical personnel, and the public into accepting vaccinations.
There's some very useful information here: http://www.vaccinationcouncil.org/2012/02/18/the-deadly-impossibility-of-herd-immunity-through-vaccination-by-dr-russell-blaylock/
Not a myth - just simple math.
Just because an immunity may wane does not make it ineffective. A high efficacy combined with a high vaccine rate can still 'starve' out a disease - exactly like we did with smallpox and polio.
Data on measles:
And 4-12 years is a little bit of a misrepresentation:
Source: https://thoughtscapism.com/2015/04/20/the-simple-math-of-herd-immunity/
And its spelled 'propagated'.
You are welcome to the last word, but I would recommend doing additional research beyond a blog with absolutely no reference or external sources. Confirmation bias is a hell of a thing.
It's obviously not going to be a productive discussion when I'm being suspected of 'confirmation bias' (i.e I'm illogical in comparison to you). The link was intended to explain my viewpoint, but I see this has devolved rapidly into trading 'references & sources' & that's a game I have no interest in wasting my time on.
Thank you for assuming that I had done only cursory research on this subject & for correcting any small spelling errors you notice, it's an endearing quality.