Letter: Herd instinct

DR CALEB McKINSTRY believes "herd immunisation" is what has protected homeopathic patients from measles (Letters, 12 September). May I point out that a certain AW Hedrick published a study of measles in Baltimore in 1933, concluding that when 68 per cent of children under 15 were immune to measles, epidemics did not occur. That was the basis of the concept of "herd immunity".

Yet in the US, with 98 per cent immunisation due to enforced vaccination, epidemics of measles still occur regularly at intervals of a few years. The fact is that after 1965 several vaccines were introduced for measles prevention. The result was that vaccinated children began contracting "atypical measles", a far more serious disease than the original form, which was usually harmless; about half the recorded deaths occurred in persons with serious chronic disease or disability.


London NW11