Public health officials persist with an MMR vaccination programme that defies common sense ("Mumps outbreak at Glasgow University", The Herald, February 16).

Mumps vaccination from the age of one with MMR, as at present, prevents safe acquisition of lifelong protection as a juvenile, wearing off just at the age when protection is really needed. No booster immunisation is currently offered when it could be, at the age of 10. Even if it were, the entire mumps vaccination campaign has created a generation, most of whom will be susceptible to mumps as adults. The occurrence of significant outbreaks of mumps in secondary schools, universities and colleges around Britain (after mumps protection has worn off) indicates that instead of solving the problem of mumps we have only postponed it to age groups when it can do the most damage. One consequence of this is that we are putting young male adults at risk of orchitis because they did not catch mumps when children. MMR vaccination is not effective in conferring full or lasting immunity across an entire population. As a result, one effect of its introduction has been to push mumps outbreaks into older age groups.

One in four males who has reached puberty and not achieved immunity to mumps runs the risk of orchitis. Orchitis (usually unilateral) has been reported as a complication in 20-30% of clinical mumps cases in post pubertal males. In about 35% of cases of mumps orchitis, some testicular atrophy occurs – this means one of the testicles shrivels up. Affected men can become sterile in one testicle. This affects one in every nine males who catch mumps after puberty compared with none who catch it before puberty. It is only because most men have two testicles and only one is affected that total sterility is rare. Most men would find that little consolation. The message seems to be it is better for a child to catch mumps naturally before puberty.

It is claimed MMR vaccination prevents infectious diseases from circulating (achieving "herd immunity") and thereby protecting the vulnerable, but as we can see with mumps vaccine, this is not the case and in fact the current scheduling exacerbates any potential problem of mumps.

Finally, how many parents are told before their child is given the MMR that the mumps vaccine is clinically unnecessary? The likely answer is, in general, "none". At the very least, administering any treatment in such a manner, especially one that puts children at risk of adverse reactions, is clearly unethical.

Bill Welsh,

President, Autism Treatment Trust,

29A Stafford Street, Edinburgh.