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244 Tetanus and Diphtheria Antibody Levels: Response to a Booster Dose in HIV-1-Infected Children under HAART
D. M. Takano*, R. C. M. Succi, A. M. Rufino, and M. I. de Moraes-Pinto
Federal Univ. of São Paulo, Brazil
Background: HIV-1-infected children present a worse response to immunization than healthy uninfected children. A faster decay in antibody levels after vaccination is also noticed. However, children under HAART might respond differently to a booster dose.
Methods: Tetanus and diphtheria antibody levels were assessed in 70 HIV-1-infected children over 2 years old (mean age = 73 months) who were regularly followed up at the Pediatric AIDS Clinic of Federal University of São Paulo, Brazil. All the children had been fully immunized against tetanus and diphtheria and were up-to-date with their booster doses. Antibody levels were tested using a double antigen enzyme immunoassay. Children who showed tetanus and diphtheria antibody levels below 0.1 IU/ml were called to receive an extra booster dose. A serum sample was collected before the revaccination and another one after the procedure. Statistical analyses employed two-tailed t test and Kruskal-Wallis test.
Results: Only 25 out of 70 children (35.7%), although fully immunized, showed tetanus and diphtheria antibody levels above 0.1 IU/ml (full protection). Higher tetanus and diphtheria antibody levels were associated with immunological category 1 to HIV infection (Kruskal-Wallis, p = 0.007 and p = 0.012, respectively). Out of the 45 children without full protection against tetanus and/or diphtheria, 18 were assessed after an extra booster dose performed under HAART. Independently of immunological and clinical categories, all 18 children showed an increase in tetanus antibody concentrations after the booster dose; only 1 child maintained diphtheria antibody levels below 0.01 IU/ml after the procedure. Mean tetanus antibody levels before and after the booster dose were 0.106 IU/ml and 0.874 IU/ml, respectively. For diphtheria, they were 0.019 IU/ml and 0.166 IU/ml. (two-tailed t test; p = 0.00002 for tetanus and p = 0.017 for diphtheria).
Conclusions: HIV-1-infected children under HAART can have a good response to tetanus and diphtheria boosters. More frequent boosters might be an effective measure to protect this high risk population against vaccine-preventable diseases.
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