A study of the effect of simultaneous vaccination with BCG and smallpox vaccine in newborn infants.

In order to determine whether the BCG and smallpox vaccinations of newborn infants could be combined, thus saving staff, time and money, particularly in the developing countries, 696 newborn infants in Taiwan were divided into three groups and vaccinated by one of the following three methods: simultaneous vaccination with BCG and smallpox vaccine, vaccination with BCG only, and vaccination with smallpox vaccine only. On follow-up, no difference was observed between the "simultaneous" group and the "smallpox only" group in respect of either no-take rate and frequency distribution by size of vaccination lesions or reactions to smallpox revaccination at 12 weeks. Tuberculin tests at 12 weeks revealed a normal distribution in the size of tuberculin reactions with a mean of 11.94 mm and 12.19 mm respectively in the "simultaneous" group and the "BCG only" group; in the "smallpox only" group all the reactions were below 9 mm, the great majority being 0-3 mm. The author concludes that there is no interaction between primary BCG and smallpox vaccination when both vaccines are administered simultaneously, and that, despite the reported complications, simultaneous administration of BCG and smallpox vaccine in newborn infants is a safe procedure.