Duration of rubella immunity induced by two-dose measles, mumps and rubella (MMR) vaccination. A 15-year follow-up in Finland.
A national two-dose vaccination program with a combined measles, mumps and rubella (MMR-II) vaccine was introduced in Finland, in 1982, immunizing children at the ages of 14-18 months and 6 years. Antibody levels were determined from serial samples from a group of originally 350 children during 15 years. The latest samples were taken 15.5 years after the first vaccination and 70% of the children could still be reached. The aim of this study was to determine the kinetics of rubella antibodies induced by the MMR-II vaccine in these individuals. Rubella antibodies were analyzed from three different cohorts: Group I seronegative children (n=166) vaccinated at 14-18 months and 6 years, Group II seronegative children (n=139) and Group III seropositive children (n=16) vaccinated at 6 and 11-13 years. Samples collected 0-9 years after vaccination were analyzed by hemolysis-in-gel (HIG) and later samples by enzyme immunoassay (EIA) techniques. The primary vaccination induced 100% seropositivity in vaccinees with a mean zone diameter of 10 (+/-1.3), 10.2 (+/-1.1) and 11.5 (+/-0.9) mm, in Groups I, II and III, respectively. The seropositivity rate was still high at 15 years, 99%, 100% and 100% with the geometric mean titer 23, 46 and 105 IU/ml, respectively. At 15 years, antibody levels <15 IU/ml which is the suggested protective level, were found in 31, 9 and 0% of children in Groups I, II and III, respectively. Because almost a third of the individuals in Group I now, at the age of 17 years, had low levels of rubella antibodies, it is possible that rubella infections may re-emerge during pregnancy. A careful surveillance including serological follow-up is therefore very important.
Davidkin
I
I
National Public Health Institute, Helsinki, Finland. irja.davidkin@ktl.fi
Peltola
H
H
Leinikki
P
P
Valle
M
M
D000293:Adolescent; D000914:Antibodies, Viral / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D008458:Measles Vaccine / Q000008:administration & dosage / Q000276:immunology*; D022542:Measles-Mumps-Rubella Vaccine; D009108:Mumps Vaccine / Q000008:administration & dosage / Q000276:immunology*; D012411:Rubella Vaccine / Q000008:administration & dosage / Q000276:immunology*; D012412:Rubella virus / Q000276:immunology*; D013997:Time Factors; D014611:Vaccination; D017778:Vaccines, Combined / Q000008:administration & dosage / Q000276:immunology
D000914:Antibodies, Viral; D008458:Measles Vaccine; D022542:Measles-Mumps-Rubella Vaccine; D009108:Mumps Vaccine; D012411:Rubella Vaccine; D017778:Vaccines, Combined