Sixty-two volunteers were studied to determine their local cutaneous, serologic, and virologic reactions to smallpox revaccination. Of 55 subjects available for examination, 45 (82%) had major cutaneous reactions. Subjects over 30 years old were more likely to have a major reaction. An increase in complement-fixing antibody titer was found in 74% of revaccinees with a major cutaneous reaction and is felt to be the best serologic indicator of a successful revaccination. Cultures of urine and thoat swab in eight subjects after revaccination did not yield vaccinia virus. Cultures of the vaccination site demonstrated the virus to be present for a mean of 7.8 days (range 0–18 days) which coincided with separation of the vaccination scab from the skin. Presence of virus at the vaccination site did not correlate with antibody response. However, subjects vaccinated more than 3 years previously and subjects with major skin reactions shed vaccinia virus for longer periods than those vaccinated less than 3 years previously or who had equivocal reactions.
Epidemic Intelligence Service Officer, Bureau of Smallpox Eradication, Center for Disease Control.
Epidemic Intelligence Service Officer, Center for Disease Control located in the Los Angeles County Health Department, Los Angeles, California 90012.