TEN YEAR EXPERIENCE WITH FURTHER ATTENUATED RUBEOLA VACCINES IN INFANTS AND CHILDREN

Abstract

From July 27, 1965 to September 3, 1975, 1030 infants enrolled in the growth and development clinics at LAC/USC MC were inoculated with live further-attenuated rubeola vaccine singly, simultaneously or in combination with other live virus vaccines. Ages at the time of inoculation ranged from 167 days to 4½ years. The hemagglutination-inhibition (HAI) antibody responses of rubeola-susceptible (HAI <1:8) infants to rubeola vaccine was independent of other administered antigens. Seroconversion rates by age after 167 days at 23 day intervals (t½ human gamma globulin) were evaluated. After 335 days of age 90 to 96.6% of the inoculated infants developed HAI titers ≥ 1:8. Seroconversion rate to rubeola antigen in infants inoculated at 335-358 days of age was 91.4%; at 359-382 days, 92.6%; at 383-406 days, 96.6%; at 407-430 days, 94.6%; at 431-454 days, 93.3%; at 455-478 days, 90.9%; at 479-502 days, 92.3%; at 503-525 days, 90.0%; and at ≥ 530 days, 90.9%. The seroconversion rate in children ≥ 15 months of age was similar to that seen in infants 12-14 months of age. Our findings also suggest factors other than age which may be important in the occurrence of rubeola vaccine failures.