The 23-valent pneumococcal polysaccharide vaccine (PPSV23) is recommended for immunocompromised adults at risk for invasive pneumococcal diseases. But booster doses reportedly can cause “hyporesponsiveness,” which make PPSV23 less suitable for some HIV-infected patients, according to researchers at University Division of Infectious Diseases, Siena, University of Siena, San Gerardo Hospital, University of Milano-Bicocca, Monza, and Institute of Clinical Infectious Diseases, Rome, all in Italy. These researchers cite studies that have found that the humoral response to PPSV23 is weaker in HIV-infected adults and that patients with AIDS are not protected.
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Protein-conjugated pneumococcal vaccines (PCVs), both 7-valent and 13-valent, may prime the immune system for better, faster responses to booster doses, the researchers say, and could be an optimal primary prophylaxis strategy for HIV-infected patients. But to the best of their knowledge, they note, data regarding the effectiveness of PCV13 in HIV-positive adults are “scant,” and no studies have directly compared the immunogenicity of PCV13 with PPSV23 in those patients.
The researchers conducted 2 parallel studies of 100 HIV-infected adult outpatients who had never been vaccinated with any pneumococcal vaccine. In the first, 50 patients were given PCV13 in 2 doses 8 weeks apart; in the second, patients were given their first routine vaccination with PPSV23. A third group of 100 HIV-negative adults who received no vaccination was used for comparison.
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After immunization, IgG titers significantly increased in both study groups at each time point compared with baseline, although response to serotype 3 was blunted in the first group. Antibody titers for each antigen did not differ between the groups at week 48. Seroprotection and seroconversion to all serotypes were comparable.
Over time, the researchers observed a “marked decrease” in IgG levels with both vaccines.
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Both vaccines were safe and well tolerated; no relevant adverse reactions were seen in either group. No HIV-infected patients developed Streptococcus pneumoniae infection during the follow-up.
