Immunizing HIV-positive adults against pneumococcal disease with the 13-valent conjugate vaccine (PCV13), years after they had received the 23-valent pneumococcal vaccine (PPSV23), boosted their immune response in a 329-person open-label study.
The researchers -- and independent experts -- believe the findings support the use of PCV13 in HIV-positive adults, and the U.S. Centers for Disease Control and Prevention (CDC) recommends the vaccine for this population.
Because of their weakened immune system, people with HIV have a six- to 324-fold higher rate of invasive pneumococcal disease than HIV-negative people. PPSV23 is recommended for HIV-positive people. But authors of the new study observed that the magnitude and duration of responses to PPSV23 may be limited, and data on its effectiveness in people with HIV have proved inconsistent.
U.S. researchers conducted this open-label study to assess the immunogenicity of the newer PCV13 in HIV-positive adults who had one or more doses of PPSV23. A conjugate vaccine induces amnestic responses, which can promote longer effectiveness duration and a booster response. Investigators at 15 U.S. centers enrolled people with a CD4 count ≥ 200 and a viral load < 50,000 copies/mL, no opportunistic infections, and no history of culture-proved Streptococcus pneumoniae infection. Participants received the PCV13 vaccine over three visits, six months apart, then had three follow-up visits.
Of the 329 study participants, 80% were men, 67% white, 25% black and 15% Hispanic. The average age was 47 years, and 95% were taking antiretroviral therapy. The average CD4 count was 605 and the average viral load was 630 copies/mL. Three quarters had a viral load below 50 copies/mL. An average 3.7 years had passed since their last PPSV23 dose, and half had received two or more PPSV23 doses.
Immunoglobulin G (IgG) geometric mean concentrations (GMC) to the PCV13 vaccine serotypes were relatively low before vaccination and rose after vaccination, with a trend toward slightly higher GMCs after the second and third vaccinations. Geometric mean titers measuring opsonophagocytic response to all PCV13 serotypes rose after the first dose and were similar or modestly higher after the second and third doses. Improvements in IgG and opsonophagocytic response to PCV13 were similar in people who had one previous dose of the PPSV23 vaccine and those who had two or more doses.
Injection site pain, usually mild, was the most common local reaction. Few severe injection site or systemic reactions occurred. After one, two and three doses of PCV13, safety findings were similar to those seen after a single dose of PCV13 or PPSV23 in a previous study of HIV-negative adults.
In an editorial on this study, two pneumococcal disease experts wrote that, because "PCV13 stimulates vigorous immune responses among HIV-infected adults, even those previously vaccinated with PPSV23," HIV providers should act "immediately ... to accomplish high vaccine coverage rates and to ensure the best possible protection against pneumococcal disease among HIV-infected adults." The CDC recommends both PCV13 and PPSV23 for adults with HIV infection.
Mark Mascolini is a freelance writer focused on HIV infection.