Effect and follow-up study on varicella vaccine.

Attenuated liver varicella vaccine (Oka strain) was used to vaccinate 242 children and 5 adults between August 1976 and December 1982; namely emergency vaccinations were given to 163 cases, including 35 high risk children, on 17 occasions, and non-emergency vaccinations were given to 84 cases including 7 high risk ones in remission. The viral doses varied from 250 to 3,000 PFU. Vaccinations prevented subsequent infection in all cases. Emergency vaccinations were given within 100 h after contact of the subjects with cases of varicella. Humoral and/or cellular immunity was acquired in 97.6% (40/41) of the high risk group and 91.8% (179/195) of the non-high risk group. As clinical reactions, rashes and fever developed in 43.9% (18/41) and in 17.0% (7/41) of high risk patients, and 7.8% (16/204) and 1.0% (2/204) of the non-high risk patients respectively. Reactions were generally slight, but were severe or atypical in 3 immunocompromized patients. Follow-up studies were carried out every year since 1980. Among the 41 high risk patients, herpes-zoster developed in 4, and varicella in 5 patients. Among the 179 non-high risk patients, there were no cases of herpes-zoster but 21 cases (12.3%) of varicella, which were mostly extremely mild. Six patients were revaccinated because of their humoral and/or cellular immunity decreased, and as a result acquired an immune response again. Criteria for varicella vaccination and details of the results of vaccination and follow-up studies are described.