Pre- and Post-Vaccination Measles Antibody and Persistence Up to 5 Years of Age Among Early ART-Treated HIV-Infected, HIV-Exposed Uninfected and HIV-Unexposed Children in Cameroon

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BACKGROUND/OBJECTIVE: Variations in measles vaccine antibody response by age and HIV status have been reported. This study assessed measles pre-vaccination status and compared humoral response durability over the first five years of life among HIV-infected (HI) children on early treatment, HIV-exposed uninfected (HEU), and HIV-unexposed uninfected (HUU) children within the ANRS 12225-Pediacam III cohort in Cameroon. METHODS: Measles vaccine (MCV) was administered at 6 and 9 months for HIV-exposed infants and at 9 months for HIV-unexposed infants, followed by a measles-mumps-rubella (MMR) dose at 15 months for all. Measles antibody titers were measured pre-vaccination, 1-6 months post-MCV doses, and annually until age 5 using ELISA (Enzygnost, Dade Behring). RESULTS: A total of 496 children were included: 143 HI (median age at cART initiation: 4.2 months, (IQR: 3.2-5.6)), 180 HEU, and 173 HUU. Of these, 456 children were tested pre-vaccination (median age: 6.1 months, IQR: 5.6-6.8), with 6.1% (95% CI: 4.1-8.6) seropositive to measles antibodies, with differences across groups. At 18.4 months (IQR: 18.1-19.9), seropositivity rates were 96.7% (59/61) in HI, 96.8% (90/93) in HEU, and 100% (111/111) in HUU groups. For children following the 6 + 9 + 15-month or 9 + 15-month MCV schedules, seropositivity at 18, 36, 48, and 60 months was 96%, 89%, 87%, and 88%, respectively, with no significant differences between groups. CONCLUSIONS: Early cART initiation in HI children may result in a robust initial measles antibody response, with comparable persistence of antibody titers across all groups up to five years.