MEASLES HUMORAL AND CELL-MEDIATED IMMUNITY IN CHILDREN AGED 5–10 YEARS AFTER PRIMARY MEASLES IMMUNIZATION ADMINISTERED AT 6 OR 9 MONTHS OF AGE

Monday, 12th of May 2014

[source]Journal of Infectious Diseases[|source]

Measles immunization of infants aged as young as 3 months has shown partial success, with failures in younger infants attributed to interference from passively acquired antibodies and to limitations of the developing immune system. Early primary measles immunization strategy was used as an effective in a measles outbreak in the United States as well as in countries where measles is endemic. Yet, information about how well measles-specific immunity persists after early primary immunization is limited. 

 In this report, the authors  evaluated the longevity of both humoral and cellular immunity to measles after early immunization by studying children aged 5–10 years, comparing those who had received their primary measles immunization at 6 or 9 months of age with those vaccinated at 12 months of age. Detailed report of the findings is accessible at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3549597/

 

 

ABSTRACT

 

BACKGROUND: Given the high infant measles mortality rate, there is interest in whether a measles immunization regimen beginning at <12 months of age provides lasting immunity.

METHODS. Measles-specific immune responses were evaluated in 70 children aged 5–10 years after primary measles vaccine administered at 6, 9, or 12 months.

RESULTS. At 5–10 years of age, the stimulation index for measles T-cell proliferation was 11.4 (SE, 1.3), 10.9 (SE, 1.5), and 14.4 (SE 2.1) when the first measles dose was given at 6, 9, or 12 months, respectively. Neutralizing antibody concentration (geometric mean titre [GMT]) in those immunized at 6 months of age was 125 mIU/mL (95% confidence interval [CI], 42–377) in the presence of passive antibodies (PAs) and 335 mIU/mL (95% CI, 211–531) in those without PAs; in those immunized at 9 months, GMTs were 186 mIU/mL (95% CI, 103–335) and 1080 mIU/mL (95% CI, 642–1827) in the presence and absence of PAs, respectively. The GMT was 707 mIU/mL (95% CI, 456–1095) when vaccine was administered at 12 months (P ≤ .04).

CONCLUSIONS. Measles-specific T-cell responses were sustained at 5–10 years of age regardless of age at time of primary measles immunization. Neutralizing antibody concentrations were lower in cohorts given the first vaccine dose at 6 months of age and in the presence of PAs; however, responses could be boosted by subsequent doses. Starting measles vaccination at <12 months of age may be beneficial during measles outbreaks or in endemic areas.