Immunization in children with HIV seropositivity at birth: Antibody response to polio vaccine and tetanus toxoid

Objective: To evaluate the humoral response to routine childhood immunization of HIV-infected children. Design: Response rate, antibody titres and persistence after polio and tetanus vaccination were compared in 72 children with HIV seropositivity at birth and divided according to HIV infection status as determined by clinical and laboratory tests. Methods: Polio antibodies were titred in a microneutralization test (positive titres,≥1:4), and antibody to tetanus toxoid with a passive haemagglutination method (protective titres,≥1:1024). Results: The response rates to polio and tetanus vaccination (>80 and >75%) were similar in the HIV-infected and non-infected children, as were antibody levels. In the subgroup with sera obtained some months after the last dose of vaccine, polio antibody levels decreased in all four HIV-infected and in three of the seven non-infected children; protective tetanus antitoxin levels were detected in three of the six infected and in all three non-infected children. Conclusions: This study demonstrates the ability of children with HIV infection to respond adequately to the two vaccines considered, although tetanus antitoxin levels were inferior, compared with those in the seroreverted children. The unsatisfactory antibody levels observed in the admittedly few HIV-positive children studied some months after the last vaccination could be the result of a lower initial protective level and not necessarily an expression of severely impaired immunocompetence. The administration of booster doses in addition to the traditional immunization schedule could be useful in children with HIV infection.