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Immunogenicity of Revaccination with Pneumococcal Vaccine in HIV-Infected Patients on Combination Antiretroviral Therapy C. FLEMING*, J. CILENTO, K. STEGER, E. MCNAMARA, S. PELTON, and D. CRAVEN.
Boston Med. Ctr. and Boston Univ. Sch. of Publ. Hlth., MA Obiective: To assess the serological response to revaccination with 23-valent pneumococcal vaccine (Pneumovax(r)) in HIV-infected adults on ART.
Methods: 25 HIV-infected adults on ART who had previously received Pneumovax(r) were revaccinated: 18 were male; mean age was 43 years, and all were receiving a protease inhibitor in combination with two nucleoside analogues. Antibody titers were determined by enzyme immunoassay (EIA) for pneumococcal capsular serotypes 6, 14, 19, and 23 immediately before and 1-4 months post vaccination. A significant serological response was defined as a two-fold increase in serotype specific IgG antibody concentration.
Results: At the time of revaccination, subjects had received ART for a mean time of 432 days with a mean increase in CD4 count of 131 cells/ml. 21 of 25 patients had an undetectable viral load by bDNA assay (<500 copies/ml) and 4 had a viral load level <3,500 copies/ml. No adverse reactions to the vaccine were reported. Pre-vaccine geometric mean anticapsular IgG concentrations were 3.27, 5.54, 6.61 and 2.74 µg/ml for serotypes 6, 14, 19 and 23, respectively, and 4.74, 6.63, 8.38 and 3.27 µg/ml, respectively, post vaccination (NS). A two-fold or greater rise in antibody concentration occurred in 7 (28%), 3 (12%), 4 (16%) and 1 (4%) of subjects for serotypes 6, 14, 19, and 23, respectively. Analysis of antibody responses by prevaccination antibody concentration (<2µg/ml and >2µg/ml) failed to demonstrate any difference in response.
Conclusion: Serological response to Pneumovax(r) revaccination is poor in HIV infection, even in patients who are well controlled on ART. Response to vaccine was not affected by prevaccine antibody concentrations. Further studies are needed to determine the functional activity of these antibodies.
Key Words: HIV infection, pneumococcus, vaccine
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