Safety and Immunogenicity of Early Measles Vaccination in Children Born to HIV-Infected Mothers in the United States: Results of Pediatric AIDS Clinical Trials Group (PACTG) Protocol 225

Background. PACTG (Pediatric AIDS Clinical Trials Group) 225, a multicenter, randomized, open-label trial in the United States evaluated reactogenicity and immunogenicity of 2 vaccination regimens: monovalent measles vaccine (Attenuvax) at 6 months of age and measles, mumps, and rubella, live attenuated (MMRII) vaccine at 12 months of age (2D), or only MMRII at 12 months of age (1D) in human immunodeficiency virus infected (HIV-infected) (POS) and uninfected (NEC) children in the pre-highly active antiretroviral therapy (pre-HAART) period. Methods. Plaque-reduction neutralization (PRN) of measles-neutralizing antibody titers were evaluated at study weeks 0, 6, 26, 32, 52, and 130 (similar to 3 years of age). Results. The 110 subjects included: 65 2DNEG; 30 1DNEG; 7 2DPOS and 8 1DPOS. Vaccinations (n = 175) were associated with no adverse experiences >Grade 2 except for Grade 3 fever (n = 2, 1 1DPOS and 1 1DNEG). Six weeks after Attenuvax, all 2DPOS subjects (7/7) seroresponded (PRN titers >= 120 mlU/mL) with median titers significantly exceeding 2DNEG titers (2115 vs 628 mlU/mL, respectively; P = .023). At similar to 3 years of age, 67% 1DPOS (4/6) and 83% 2DPOS (4/5) subjects maintained titers >= 120 mlU/mL. Prevaccination titers >= 25 mlU/mL among 2DNEG subjects correlated inversely with the likelihood of achieving titers >= 120 mlU/mL (56% vs 90%; P = .004). Conclusions. Among HIV-infected children pre-HAART, Attenuvax at 6 months was well tolerated and immunogenic. These data support the current World Health Organization (WHO) recommendation to administer a first dose of measles vaccine at 6 months of age to HIV-infected children.