The diphtheria vaccine debacle of 1940 that ushered in comprehensive childhood immunization in the United Kingdom.

In January 1940 British Ministry of Health circular 1307 proposed the introduction of mass childhood diphtheria immunization. This was a policy reversal after a decade during which opportunities for diphtheria prophylaxis were ignored, or resisted on grounds of cost. Diphtheria toxoid was to be the first of many centrally funded childhood immunizations in the UK and it set a pattern that has now held good for over 70 years. The circumstances in 1940 were particularly fortuitous, and diphtheria toxoid has since given successive generations of children a lifetime's protection from the disease; but difficulties have been experienced in introducing and evaluating some of the more recent immunizations, and in maintaining and justifying them in the face of parental scepticism and academic or pressure-group opposition, however ill-founded this may have been. The task of decision-making with regard to new candidate vaccines demands a careful balancing against the costs of the expected benefits during the recipient's lifespan.