One of the saddest and most upsetting stories over the summer was largely ignored by the media but ought to be noted and acted on by every parent. It came in the form of a press release from the Health Protection Agency, and it revealed the number of cases of measles. Shockingly, the incidence has gone up by a factor of ten in the first four months of the year compared with the same period last year.

There are two probable causes. One is the current epidemic in France, where more cases have been reported since January than the whole of 2010. We can of course avoid going to France, but we can’t do much about the prevalence of the disease there. What is as a direct result of decisions taken by thousands of well-meaning but misinformed parents is the fact that many children, and those who are now young adults, have been left unprotected against measles because of the reluctance which was distressingly common a few years ago to allow immunisation with the MMR vaccine. The latest cases are mainly among unvaccinated people under twenty five years of age.

This is sad because, far from being a negligible and unimportant childhood disease, measles is nasty. It’s highly infectious and potentially very dangerous. Apart from the disease itself, measles can lead to pneumonia, eye and ear infections, croup, and in more serious cases inflammation of the brain, encephalitis, which can be fatal. In pregnancy it can lead to miscarriage or premature labour. And its sad because the reason why people were determined not to let their children have the MMR vaccine was as a result of now entirely discredited but much advertised research by the now struck-off doctor Andrew Wakefield. There are still people who believe he was right to link MMR vaccine to autism in toddlers. Every reputable medical researcher thinks otherwise.

But when the controversy, amplified by the ignorance of people writing articles in the press and magazines who wouldn’t understand a research paper but did understand a “newsworthy” health scare story, erupted, there were many parents who believed it. And although the rate of immunisation has now gone up again, there is a lot of people who are now at school-leaving or university age who were denied vaccination, and are now at risk.

But there is another factor at work, and that’s what is called rather unflatteringly “herd immunity”. Before the scare, measles was almost completely eradicated in the united Kingdom. The reason is that over 95% of the vulnerable population were immunised, so even if there was an isolated case, it couldn’t progress to an epidemic. If the rate of vaccination drops below that figure, then it can start to get a hold again, and that, sadly, is what seems to be happening.

So the message is clear. Check if you (or your child) are immunised, which means two doses. One is better than none, but doesn’t give full protection. The good news is that two doses prevents infection in  99% of cases. Which is reassuring, and also what we owe our children. Mr Wakefield and those who promulgated his nonsense have a lot to answer for.