RESUMO
Primary vaccination by intradermal jet injection, using diluted smallpox vaccine, was compared with multiple-pressure vaccination in 625 Jamaican children. The cutaneous and antibody response patterns were evaluated. The primary take rates among those jet vaccinated were 97 percent or more in those receiving vaccines with a titre of 10 6.3 TCID50/ml and 10 7.0 TCID50/ml, and 96 percent in those vaccinated by multiple pressure, using undiluted vaccine. The primary take rates in subjects receiving jet-injected vaccine with titre of 10 6.0 TCID50/ml and 10 5.0 TCID50/ml were 90 percent and 62 percent respectively. Among subjects tested who developed Jennerian vesicles, there was also a failure of neutralizing-antibody development. Vesicle and scar sizes were generally smaller in the jet-vaccinated subjects than in those vaccinated by the multiple-pressure technique. Infants tolerated jet vaccination without difficulty. Vaccinial complications did not occur in any subject. The intradermal jet injection of 0.1ml of vaccine with a titre 10 6.3 TCID 50/ml or higher is recommended as a highly effective method for achieving successful primary smallpox vaccination. The method appears best suited for use in mass smallpox-vaccination programmes.(AU)
