THERE is very little scientific or medical doubt about the mumps, measles and rubella vaccination. It is safe. It is wise and sensible that all children should be inoculated with it.

So why, then, have we reached the stage where up to 25 per cent of four-year-olds starting school this week have not had it?

This statistic is worrying because it means we are losing our "herd immunity" to diseases that do kill. Already children have died of measles in the Netherlands and Ireland because they had not had MMR.

The statistic shows that a growing number of parents have lost confidence in the injection. When they know a vaccine is safe, they embrace it wholeheartedly, as the stunning success of the meningitis C jab showed yesterday.

Scientifically and medically, parents' perception of MMR is irrational. However, it is understandable and our older politicians and health professionals should try to remember exactly how they felt when they carried home their first baby. It is a nervous, bewildering time. You try to do your very best for the infant and just as you've recovered from the fright of it having its first runny nose - a fright so severe you are convinced it is at death's door - you are expected to have it injected.

And injected with a vaccine that you know is safe. But in the back of your mind you know that there are 2,000 families - more than 40 from the North-East - who are suing the MMR manufacturers in the belief that the vaccine caused brain damage or autism.

It is the same dilemma parents face over beef. They've heard all the assurances and continue to enjoy the meat themselves, but when they have a child only a year old, a child which is free from any potential contamination, they become ultra-cautious.

The Government's policy at the moment is to keep hammering away with the message that MMR is safe and must be taken. It is a sensible message, but it is not working.

And now we stand on the brink of a measles epidemic which, on a purely economic level, will cost the NHS dearly.

Until recently, some GPs in the North-East were prepared to source separate vaccines for mumps, measles and rubella from the Continent so that parents had an alternative. That these stocks quickly ran out shows how keen parents were for them. This has now been stopped, largely because the single doses were old technology and didn't offer as good protection.

While the Government is right to continue its attempts to restore confidence in MMR, the time must come for it to listen to parents' fears and consider the return of the single doses for those who want them.

After all, some protection is better than none and if the single doses were available today we wouldn't be on the brink of a measles epidemic.