MMR: The myth of the herd
September 28th 2007, 13:16Health experts are concerned that the uptake of the MMR vaccine is still far too low to provide 'herd immunity' for the population. Vaccination levels have risen to 85 per cent overall following the autism scare - but they are still well below the 95 per cent recommended by the World Health Organization in order to achieve global protection from the disease.
The premise that supports the herd immunity theory is, of course, that the vaccine works, and offers years of protection.
But, at best, it works for some of the people some of the time - a fact that governments and health officials are loathe to reveal.
For instance, more than three-quarters of all measles cases in the UK that were diagnosed between 1985 and 1986 had been properly vaccinated. A similar pattern can be found in the USA. In one outbreak in 1986 in Corpus Christi, Texas, 99 per cent of affected children had been vaccinated. It's a picture that applies across the whole of the USA where 80 per cent of all cases of measles occur in vaccinated children.
Even if the MMR provides some kind of protection at the time, it also seems to transfer the problem to later years. Before vaccinations became a national pursuit, 90 per cent of all cases of measles occurred in children aged between five and nine.
Now up to 64 per cent of measles cases are among the over-10s.