Tetanus immunity after diphtheria, tetanus toxoids, and acellular pertussis vaccination in children with clinically stable HIV infection

Background: HIV infection often impairs the immune response to childhood vaccines. Objective: We sought to study the ability of HIV-infected children receiving highly active antiretroviral therapy (HAART) to generate a booster response to immunization with a recall antigen to which they had lost humoral immunity. Methods: Diphtheria, tetanus toxoids, and acellular pertussis (DTaP) vaccination was given at either 16 or 36 weeks after initiation of HAART to 37 HIV-infected children 2 to 9 years of age with a history of DTaP or diphtheria-tetanus-pertussis receipt who had negative tetanus antibody titers (≤1:243) at baseline. Results: There was a clear increase in tetanus titers after vaccination, with an increase of 27-fold over the baseline values at weeks 4 and 8. The effect on tetanus titers faded to a 9-fold and 3-fold increase over baseline values at weeks 18 and 32, respectively. DTaP vaccination did not affect HIV-1 RNA viral load or CD4 percentage or cell count. There was no increase in either acute or long-term adverse events associated with the DTaP vaccination. Conclusion: Although children with stable HIV infection receiving HAART can mount antigen-specific responses to tetanus immunization, the durability of these responses might be limited. Long-term monitoring of specific immune function in such children is indicated.