Adverse reactions after smallpox vaccination.

Nine hundred and thirty-eight reports of adverse reactions of smallpox vaccination in Australia between 1960 and 1976 have been analysed according to the type of reaction, and the age and sex of vaccinee. In an estimated 5,000,000 vaccinations, the reaction rate was 188/million, and the death rate 1-5/million. Generalized vaccinia was the most common reaction. The more serious reactions--eczema vaccinatum, progressive vaccinia, and neurological and cardiac complications--accounted for 7-4% of the reports. A small number of rarely reported non-specific inflammatory reactions is also included. There was a marked difference in the number of reactions reported in females and males (the female-male ratio was 1-6:1), and this difference increased with age. Paradoxically, of eight reports of cardiac complications, seven concerned males. The administration of vaccinial immune globulin was usually followed by a rapid resolution of the adverse reactions.