The term, ‘herd immunity’, was coined by researcher, A W Hedrich, after he’d studied the epidemiology of measles in USA between 1900-1931. It theoreticaly should be a form of protection from infectious disease that occurs when a large percentage of a population has become immune to an infection,
Disease-conferred immunity usually lasted a lifetime. As each new generation of children contracted the infection, the immunity of those previously infected was renewed due to their continual cyclical re-exposure to the disease; except for newly-infected children and the few individuals who’d never had the disease or been exposed to it, the ‘herd immunity’ of the entire population was maintained at all times.
Vaccine induced immunity is depends on several variables such as vaccination coverage, efficacy of the vaccination, it’s duration and the treshold of the immune population needed for existence of the herd immunity.
With this calculator you can calculate whethet there was or not, a herd immunity present in allmost every part of the world in given year in the past.
The variables are as follows:
|Measles||27y||(Ramsay ME, 1994)|
|Pertusis||5y||(Al Dajani, Scheifele, PCH 2007)|
|Diphteria||7y||(Girr, Fisman, Padiatrics 2015)|
|Hepatitis B||6y||(EJE, 1995)|
|Yellow fever||10y||(Ammana, Slifka ERV, 2016)|
The result shows if there was a herd immunity in the chosen country/region in the chosen year for the chosen disease.