Vaccination against smallpox.

Correspondence Because of heavy pressure on our space, correspondents are asked to keep their letters short. SIR,-During the decade 1951-60 there were 21 deaths in England and Wales due to smallpox. In the same period there were 27 deaths, most of them infants, attributed to post-vaccinal encephalitis as well as a score or so deaths from other fatal complications of smallpox vaccination. As Professor G. W. A. Dick (November 17, p. 1275) points out these figures may well underestimate the risk. Whatever one's views may be on the need for routine vaccination it must be generally agreed that the procedure should be conducted at the age when the risk is minimal. Smallpox (page 356) he will find that during the period 1951-8 there were in England, Wales, Scotland, and part of Northern Ireland 36 infant deaths attributed to the complications of smallpox vaccination and 2,343,908 primary vaccinations in infancy. At ages 1-4 years the figures were one death and 538,529 primary vaccinations. The statistical odds against the 37 deaths being distributed in this way, if the risk was identical in the two age periods, is less than one in a hundred. No estimates have been published, so far as I know, of the relative risks of primary vaccination at different periods during the first year of life. Dr. Hargreaves's figure for " unavoidable" post-vaccinal mortality of 5.9 per million at ages 4-12 months may be a serious underestimate depending on how many of the 2,671,488 primary vaccinations in infancy on which the rate is based were performed before the age of 4 months. There must have been a substantial number, as there were 10 post-vaccinal deaths in this age range. It may well be that the risk of fatal complications is no higher during the second six months of life than during the second year. Until data on this point are available, however, all that can be asserted, on the evidence quoted, is that the risk is higher under the age of 1 year than over that age.-I (November 17, p. 1275) raises so many questions that another viewpoint may be useful. One of his main arguments is based on the assumption that the complication rate in elderly persons, primarily vaccinated. is less than in infants. He quotes statistics compiled by Griffith' from England. Scotland. and Wales. He himself has some doubts about the reliability of these figures. Dixon. who …