A newer pneumococcal vaccine that aims to protect against pneumococcal pneumonia and other serious pneumococcal diseases stirred up immune system responses in HIV-positive adults who got an earlier type of pneumococcal vaccine.1 Immune responses were similar whether people got one or more shots of the previous vaccine.
Because HIV-positive people have a weakened immune system, they run a high risk of infection with Streptococcus pneumoniae ("strep"), which causes pneumococcal pneumonia and invasive pneumococcal disease. Studies show that people with HIV can have a 40 times higher rate of invasive pneumococcal disease,2 which means Streptococcus pneumoniae invading blood or spinal fluid (Figure 1). HIV-positive people also have higher rates of severe pneumococcal disease and repeated pneumococcal disease.
Figure 1. Streptococcus pneumoniae can cause strep pneumonia and can invade spinal fluid (shown here) or blood. HIV-positive people run a much higher risk of invasive pneumococcal disease than people without HIV, but vaccines like PCV13 and PPSV23 can prevent pneumococcal disease. (Photo from Dr. M.S. Mitchell, Centers for Disease Control and Prevention's Public Health Image Library (PHIL), identification number 1003.)
Many people with HIV got a pneumococcal vaccine called PPSV23 (for 23-valent pneumococcal polysaccharide vaccine), which has been available since 1983. But the size and duration of responses to PPSV23 may be limited.3
Research shows that another kind of pneumococcal vaccine -- called a pneumococcal conjugate vaccine (PCV) -- can prevent pneumococcal disease including pneumonia in children. Five years ago a trial found that a vaccine called PCV7 prevented pneumococcal disease in HIV-positive adults who recently had pneumococcal disease.4 U.S. researchers conducted a new study to see if a new vaccine, PCV13, stimulates an immune system response in HIV-positive adults already vaccinated with PPSV23.
The study took place at 15 U.S. medical centers between November 2009 and May 2012; it included HIV-positive adults who had 1, 2, or 3 doses of the PPSV23 vaccine at least 6 months before PCV13 vaccination began in this study. Everyone had a CD4 count at or above 200 and a viral load below 50,000 copies. All study participants had taken the same antiretroviral combination for at least 6 weeks or were not taking antiretrovirals. No one had an active AIDS disease, cancer, a serious chronic disease, or Streptococcus pneumoniae infection.
Study participants made six clinic visits. At the first visit, then 6 and 12 months later, they got the PCV13 vaccine. The three other visits came 1 month after each vaccine visit; at these three visits, health workers collected blood samples to measure responses to the vaccine. Researchers used two ways to measure antibodies in blood samples -- one measured the levels of specific antibodies called anticapsular IgG and the other measured the activity of antibodies, called opsonophagocytic activity (OA).
Antibodies are proteins that an effective vaccine produces to help the immune system prevent or control an infection, in this case Streptococcus pneumoniae infection. The vaccine is called PCV13 because it aims to promote immune system activity against 13 types of pneumococcus.
Of the 329 people who entered the study, 80% were men. Study participants averaged 47.3 years in age, two thirds were white, 25% were black, and 15% were Hispanic. Almost everyone (95%) was taking antiretroviral therapy, and 74% had an undetectable viral load. CD4 count averaged 605 in the study group. Among the 329 people who got at least one PCV13 dose, 300 (91%) got two doses and 279 (85%) got three doses.
An average 3.7 years had passed since these people had a dose of the PPSV23 vaccine. About half had one dose of PPSV23 and half had two or more doses.
IgG antibody responses against Streptococcus pneumoniae were low before PCV13 vaccination began. Each PCV13 vaccination -- the first, second, and third dose -- produced an IgG antibody response. Responses after the second and third dose were slightly higher than after the first dose. IgG levels after PCV13 vaccination were similar in people who had one previous PPSV23 dose and in those who had two or more PPSV23 doses.
OA antibody responses were higher 1 month after the first PCV13 dose than before that first dose. Compared with the OA antibody response after the first PCV13 dose, OA antibody responses were similar or slightly higher after the second and third PCV13 doses.
The proportion of participants who had a local reaction to the vaccine shot (redness, swelling, or pain) did not differ from one shot to the next. Under 10% reported redness, about 10% reported swelling, and about 80% reported pain. Most of these reactions were mild or moderate; very few were severe.
The most frequent general-body problems after vaccination were fatigue, headache, and new general muscle pain. Almost two thirds of study participants had some clinical problem after vaccination (like upper respiratory tract infection, fatigue, diarrhea, bronchitis, and rash). No severe problem like this could be linked to the vaccine.
Overall safety findings in this study were similar to those in HIV-negative adults getting one shot of PCV13 or one shot of PPSV23.
This study of more than 300 HIV-positive people found that the PCV13 vaccine produced important immune system responses against all 13 pneumococcus types targeted by the vaccine. Previous research suggested that adults vaccinated with the PPSV23 pneumococcal vaccine would have lower responses to later vaccination with another pneumococcal vaccine. But that did not happen in this study, in which all participants had one or more PPSV23 shots in the past and still responded to the PCV13 vaccine. That finding is important because many HIV-positive adults already had one or more doses of PPSV23.
In an article written about this study, two HIV experts list other strategies that can help HIV-positive people avoid pneumococcal disease:2
But the most direct way to avoid pneumococcal disease, these experts stress,2 is getting a pneumococcal vaccine like PCV13 or PPSV23. Current U.S. guidelines call for PCV13 vaccination when HIV is diagnosed in adults, followed by the PPSV23 vaccine 8 or more weeks later.5 HIV-positive adults who have already had PPSV23 vaccination should get one PCV13 vaccine dose 1 or more years after the last PPSV23 dose.
The researchers who conducted this study1 and the experts who analyzed it2 note that the results do not support use of three PCV13 doses, each given 6 months apart, as in this trial. More studies will be needed to determine whether more than one PCV13 dose may help HIV-positive people avoid pneumococcal disease longer.
The bottom line for people with HIV and their providers is that this study supports U.S. guidelines recommending PCV13 for people with HIV infection, even if they have had PPSV23 vaccination. The experts who reviewed this article say the findings "should immediately be used by providers to accomplish high vaccine coverage rates and to ensure the best possible protection against pneumococcal disease among HIV-infected adults, by the administration of both PCV13 and PPSV23 vaccinations."2
|PCV13 Pneumococcal Vaccine Boosts Immunity in Adults With HIV and Prior PPSV23 Vaccination|
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