Clinical and serological studies on CAM-70 live attenuated measles vaccine: an 18-year survey at a pediatric clinic in Japan.

Live attenuated measles vaccine chorioallantonic membrane-70 (CAM-70) was administered to 471 healthy individuals over an 18-year period (1982-1999) at the pediatric clinic of Showa Hospital in Japan. Seroconversion occurred in 95.4% (418/438) of initially seronegative subjects. Reactions to the vaccine were generally insignificant, except for vaccine-related fever in about 20%. In February 2000, we made a questionnaire survey of 272 initially seronegative subjects who were vaccinated, from 0.7 to 18.1 years (mean: 5.5 years) earlier. Six (2.2%) of them contracted breakthrough measles during follow-up. The vaccine was generally safe and effective. However, it warrants investigation that the incidence of breakthrough measles may increase in the future in Japan.