Clinical and serologic study of four smallpox vaccines comparing variations of dose and route of administration. Primary subcutaneous vaccination.

As part of a large study designed to develop schedules for smallpox immunization with reduced morbidity, 799 children received primary immunization with subcutaneous vaccine. Four vaccines (New York City Board of Health calf lymph, New York City chorioallantoic membrane, CV-1 and Lister) at three dosages (l0(3), 10(4), 10(5) pock-forming units) were administered. Eighty-two percent responded with hemagglutination-inhibiting antibody at one month, and only 22% with neutralizing antibody. There was no correlation between concentration of vaccine and antibody response. The CV-1 strain was slightly but significantly less likely to induce antibody than the other three vaccines. Subcutaneous vaccination was not associated with significant temperature elevation in general. However, some children developed erythema at the vaccination site or a swollen arm, and fever did tend to occur in this small group. Four children developed nonspecific vaccinia-related rashes, and one had generalized vaccinia.