Evaluation of Immune Response to Measles Component of MMR Vaccine in Children with HIV Infection Receiving Antiretroviral Therapy

Background: Children with HIV (CLHIV) respond poorly to primary immunization with measles vaccine and those responding tend to lose protective titer of antibodies by 2-3 years old. Revaccinating CLHIV after immune reconstitution with antiretroviral therapy (ART) may result in good seroconversion, thereby conferring them protection from measles. The objective was to study prevalence of measles antibodies in CLHIV receiving ART before and after immunization with MMR vaccine. Methods: CLHIV in the age 5-18 years receiving ART for >6 months and with CD 4 count >15% were included in this prospective study. Their serum was assayed for IgG measles antibodies by qualitative immune-enzymatic determination using enzyme linked immunosorbent assay. The subjects were then immunized with a single dose of MMR vaccine. A repeat venous sample was assayed for measles antibodies 8-12 weeks after immunization. Results: Sixty-six subjects (46 males, 20 females, mean age 10.4 +/- 2.8 years) were enrolled. The mean duration of ART was 3.4 +/- 1.5 years and median CD4 count 716.5 mu/L (interquartile range: 563.3-950). At enrollment, 16 (24.2%) subjects tested positive, 8 (12.1%) equivocal and 42 (63.6%) negative for measles antibodies. After 8-12 weeks of immunization, 62 (93.3%) tested positive, 1 (1.5%) equivocal, and 3 (4.5%) negative. There was no difference among the seropositive and seronegative subjects postimmunization with respect to age, sex, duration of ART, nutritional status, CD4 count, or WHO clinical stage. No serious adverse reaction was observed to vaccination. Conclusions: MMR vaccine leads to an excellent seroconversion to measles component of vaccine in immune-reconstituted CLHIV.