One problem with the immunity from vaccination is that it falls away over time far quicker than naturally acquired protection. Immunity after catching measles is usually life-long. After a single vaccine protection may last 25 years, longer in some, shorter in others. No one knows how many vaccinated people will still be protected against measles, mumps or rubella in 25 or 50 years time. But an educated guess can be made, by combining the results of studies that have measured antibody levels in children after one or two MMR vaccinations.1 2 3 4 5 6 7 8
It is probable that people’s immunity to all three illnesses will steadily fall as they get older, with the likelihood that, by middle age, many will no longer be immune. As it is extremely unlikely that these illnesses will be eradicated, that means that, for the first time in history, older people are may be catching measles, mumps and rubella in large numbers– with unknown consequences.Some scientists have made alarming predictions of the consequences of this falling protection. The vaccination ‘time bomb’ The period in which we are now – the first generation since the introduction of the MMR – has been described as the ‘honeymoon’ period. Most people born before the early 1970s will have life-long natural immunity, but those born later have vaccine protection, that is likely to fall away. Research published in 2006 found that people born before the introduction of immunisation were more likely to have high levels of antibody to measles, mumps and rubella than those born in the vaccine era.10 After 20, 30 or 40 years a lot of vaccinated people are likely to become susceptible to the illnesses again as their protection from vaccination wears off. This may lead to a resurgence of the diseases. Only this time the diseases could be different from what we knew before vaccination. How different, only time will tell. On the optimistic side, most people may still have some remaining protection from vaccination and so the illness may generally be mild. On the pessimistic side, there are two things to worry about: the first is that the illnesses will affect older people in whom the side-effects are likely to be more serious; the second is less certain but more concerning: the wild measles virus has been changing, or mutating, so that it is becoming less like the measles vaccine virus. Whilst there is no evidence that this has caused any problems yet, the vaccine may not protect against future mutations. We meddle with nature at our peril. The worst case scenario is that we will have changed measles, as a direct result of vaccination, from a relatively harmless illness to which we had adapted successfully to a more dangerous illness, with unknown consequences for future generations.