DURATION OF THE IMMUNE-RESPONSE TO MMR VACCINE IN CHILDREN OF 2 AGE-DIFFERENT GROUPS

A combined vaccine against measles, mumps and rubella (MMR) was admini stered to both a group of children aged 10-12 months simultaneously wi th booster doses of compulsory diphtheria-tetanus toxoids and oral pol iovirus vaccine and a group of children aged 15-24 months who had prev iously received booster doses of the compulsory vaccines. Apart from o ne subject belonging to the second group who was non responder and one from the same group who did not seroconvert against the mumps virus a lone, 5 to 6 weeks after MMR vaccine administration we found protectiv e levels of antibodies against measles, mumps and rubella viruses in a ll children. The follow up of both groups at 3 years did not reveal di fference between the two groups. Protective levels of serum antibodies against measles and mumps were found in the two groups, altough a sig nificant decline of rubella antibodies was shown (p < 0.05). Since the immunogenicity of the vaccines in the two groups did not differ, we r ecommend that the scientific community reconsider the vaccination sche dule until now recommended. In our opinion the MMR vaccine should be a dministered simultaneously with booster doses of diphtheria-tetanus to xoids and oral poliovirus vaccine at 10-12 months of age because this policy improves parents' compliance, markedly reduces community costs and simplifies routine immunization schedule.