Immunity to measles before and after MMR booster or primary vaccination at 12 years of age in the first generation offered the 2-dose immunization programme.

In 1982, a 2-dose regimen was introduced in Sweden for the combined vaccination against measles, mumps and rubella (MMR) in children aged 18 months and 12 years. In 1993, blood samples from 378 12-year-old children, i.e. the first age-group receiving a MMR booster, were collected prior to and 2 months after the vaccination. 82% had a certificate of a previous measles (M) or MMR vaccination (group I). The remainder was classified as children with 'no documentation' (group II). In group I, 5 (1.5%) lacked demonstrable antibodies to measles prior to the booster; in group II this figure was 39%. The pre-booster antibody pattern was similar in M vaccinees and MMR vaccinees. After the vaccination, 1 of the 378 children was seronegative. In both groups, children with low pre-vaccination levels responded with a titre rise, in accordance with a similar study 6 years earlier.