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PPSV23 protective against severe IPD, not pneumonia, in older adults
The 23-valent pneumococcal polysaccharide vaccine demonstrated efficacy against the most severe invasive forms of pneumococcal disease in patients aged 65 years and older, but the vaccine showed a lack of protection against hospital-treated pneumonia, researchers reported.
There has been unsufficient evidence supporting the effectiveness of the 23-valent pneumococcal polysaccharide vaccine (PPSV23; Pneumovax 23, Merck) against pneumonia and whether the vaccine should complement the 13-valent pneumococcal conjugate vaccine (PCV13; Prevnar13, Wyeth) or be replaced by it. To address this issue, the Advisory Committee on Immunization Practices recently recommended administering both vaccines to older patients.
In a retrospective, case-controlled study, researchers evaluated the effectiveness of PPSV23 in preventing invasive pneumococcal disease (IPD) and hospital-treated pneumonia (HTP) — the most resource-intensive form of community-acquired pneumonia. They accessed electronic medical record data on 470,070 patients aged 65 years and older from a large health care provider and payer organization in Israel that covers more than half of the country’s population.
In Israel, the current recommendations are to give PPSV23 to patients aged 65 years and older and to older adults with certain risk factors, and to administer PCV13 in the pediatric population.
The researchers identified cases of IPD (n = 212) and HTP (n = 23,441) diagnosed from 2008 through 2010. Matched controls without IPD or HTP were randomly selected based on gender, birth year and risk score. The researchers evaluated vaccine effectiveness for PPSV23 using multivariable logistic regression analysis.
Results indicated that 41.5% of IPD cases had undergone vaccination vs. 51.4% of controls (P = .01). Among the HTP cases and controls, however, the difference in the percentage of those vaccinated was negligible (54.6% vs. 52.9%; P < .01). Both unadjusted and adjusted associations between vaccination and IPD showed a protective effect (adjusted OR = 0.58; 95 % CI, 0.41-0.81), while neither adjusted nor adjusted relationships between vaccination and HTP showed a protective effect (aOR = 1.01; 95% CI, 0.97-1.04).
The researchers also conducted sensitivity and subgroup analyses, which primarily showed similar results.
“Our results suggest that while the PPSV23 vaccine is effective against the most severe invasive forms of pneumococcal disease, there is still a need for a vaccine that effectively protects against pneumonia,” the researchers wrote. “As national vaccination policies are adapted according to emerging evidence on PCV13’s efficacy, the lack of effectiveness of PPSV23 in protecting against all-cause pneumonia should be considered.”
Disclosure: The researchers report no relevant financial disclosures.