HIV-infected children living in Central Africa have low persistence of antibodies to vaccines used in the Expanded Program on Immunization.

The Expanded Program on Immunization (EPI) is the most cost-effective measures to control vaccine-preventable diseases. Currently the EPI schedule is similar for HIV-infected children; the introduction of antiretroviral therapy (ART) should considerably prolong their life expectancy. To evaluate the persistence of antibodies to the EPI vaccines in HIV-infected and HIV-exposed uninfected children who previously received these vaccines in routine clinical practice we conducted a cross-sectional study of children aged 18 to 36 months born to HIV-infected mothers and living in Central Africa. We tested blood samples for antibodies to the combined diphtheria tetanus and whole-cell pertussis (DTwP) the measles and the oral polio (OPV) vaccines. We enrolled 51 HIV-infected children of whom 33 were receiving ART and 78 HIV-uninfected children born to HIV-infected women. A lower proportion of HIV-infected children than uninfected children had antibodies to the tested antigens with the exception of the OPV types 1 and 2. This difference was substantial for the measles vaccine (20% of the HIV-infected children and 56% of the HIV-exposed uninfected children p less than 0.0001). We observed a high risk of low antibody levels for all EPI vaccines except OPV types 1 and 2 in HIV-infected children with severe immunodeficiency (CD4+ T cells less than 25%). Children were examined at a time when their antibody concentrations to EPI vaccines would have still not undergone significant decay. However we showed that the antibody concentrations were lowered in HIV-infected children. Moreover antibody concentration after a single dose of the measles vaccine was substantially lower than expected particularly low in HIV-infected children with low CD4+ T cell counts. This study supports the need for a second dose of the measles vaccine and for a booster dose of the DTwP and OPV vaccines to maintain the antibody concentrations in HIV-infected and HIV-exposed uninfected children. (authors)