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Measles immunity after revaccination: results in children vaccinated before 10 months of age
Insights
Many children vaccinated against measles before age one do not develop immunity. Revaccination, even a third dose, often fails to produce an adequate measles antibody response in these individuals.
Area of Science:
- Immunology
- Pediatric infectious diseases
Background:
- Primary measles vaccination before 1 year of age may result in suboptimal immunity.
- Assessing the effectiveness of revaccination in this cohort is crucial for public health.
Purpose of the Study:
- To evaluate measles immunity and response to revaccination in children who received their initial measles vaccine before 12 months of age.
Main Methods:
- Antibody titers and cell-mediated immunity (lymphocyte transformation) were measured in children revaccinated after primary vaccination at <10 months and >1 year.
- A subset received a third measles vaccine dose.
Main Results:
- 40% of 72 children had no detectable measles antibody; geometric mean titer was low (approx. 1:4).
- 33% of children with low titers still failed to respond after a third vaccine dose.
- Cell-mediated immunity responses did not correlate with antibody presence.
Conclusions:
- Revaccination is frequently unsuccessful in children vaccinated under 1 year of age.
- Even a third measles vaccine dose may not elicit a sufficient antibody response in this population.
Abstract:
Measles immunity was studied in children in a private pediatric practice who had been revaccinated because they had received their primary measles vaccination before 1 year of age. Antibody was measured in 72 of these children who had received the first injection of live measles virus vaccine at less than 10 months of age, and the second at greater than 1 year of age. Of the 72 children, 29 (40%) had no detectable antibody and the geometric mean titer for the group was approximately 1:4. Of the children with low antibody titers, 15 were given a third injection of measles vaccine and five (33%) still did not respond. Cell-mediated immunity as indicated by lymphocyte transformation to measles antigen was measured in 11 of the children. Five (45%) had responses to measles antigen, but the responses did not correlate with the presence or absence of antibody. This study confirms the observation that revaccination is unsuccessful in many children who received measles vaccine in the first year of life, and shows that even a third injection of vaccine may fail to produce a significant antibody response.