Immunity Following Childhood Vaccinations in Perinatally HIV-Exposed Children with and without HIV Infection in Latin America.

Background: Perinatally HIV-infected (PHIV) children are at risk for under-vaccination and poor vaccine response at 4 years of age. Childhood vaccine coverage and immune response were compared between PHIV and HIV-exposed uninfected (HEU) children in Latin America and the Caribbean. Methods: PHIV and HEU children were enrolled prospectively at 15 sites from 2002 to 2009. Full vaccination by age 4 years was defined as: 3 hepatitis B virus vaccine doses; 4 tetanus toxoid-containing vaccine doses; 3 doses of Haemophilus influenzae type b vaccine by age 12 months or >= 1 dose given after age 12 months; one measles-containing vaccine dose; one rubella-containing vaccine dose. Immunity was defined by serum antibody titer. Fisher exact test (for categorical measures) and t test (for continuous measures) were used for comparisons. Results: Among 519 children seen at age 4 years, 191 had serum specimens available (137 PHIV, 54 HEU). Among those with specimens available, 29.3% initiated combination antiretroviral therapy (cART) <12 months of age, 30.9% initiated at >= 12 months of age, and 39.8% had not received cART by the time they were seen at 4 years of age. At 4 years of age, 59.9% were on PI-containing cART (cART/PI), and 20.4% were on no ART. PHIV children were less likely than HEU children to be fully vaccinated for tetanus (55.5% vs. 77.8%, P = 0.005) and measles and rubella (both 70.1% vs. 94.4%, P < 0.001). Among those fully vaccinated, immunity was significantly lower among PHIV than HEU for all vaccines examined: 20.9% versus 37.8% for hepatitis B virus (P = 0.04), 72.0% versus 90.5% for tetanus (P = 0.02), 51.4% versus 68.8% for H. influenzae type b (P = 0.05), 80.2% versus 100% for measles (P < 0.001) and 72.9% versus 98.0% for rubella (P < 0.001) vaccine, respectively. Conclusions: Compared with HEU, PHIV children were significantly less likely to be immune to vaccine-preventable diseases when fully vaccinated. Strategies to increase immunity against vaccine-preventable diseases among PHIV require further study.