Data published in Clinical Infectious Diseases demonstrate the effectiveness of the 13-valent pneumococcal conjugate vaccine (PCV13) against hospitalization for community-acquired pneumonia (CAP) in US adults ≥65 years of age.
In September 2014, PCV13 was universally recommended to adults ≥65 years of age in the United States. A test-negative design identified cases and controls from a population-based surveillance study of adults in Louisville, Kentucky, hospitalized for CAP.
Data from a subset of 2034 people hospitalized for CAP and enrolled from April 1, 2015, to April 30, 2016, were analyzed and PCV13 serotypes were identified in 3.3% (68) of the participants. Positive blood culture was observed in 6 of these 68 (8.8%).
Identified patients hospitalized for CAP were less likely to have received PCV13 than controls (4.4% vs 14.5%); unadjusted vaccine efficacy was 72.8% (95% CI, 12.8%-91.5%).
No confounding was observed after adjusting for immunocompromised status, body mass index, and history of pneumococcal polysaccharide vaccination. The adjusted vaccine efficacy range was 71.1% to 73.3%.
Despite susceptibility to biases inherent in the test-negative design, the results here were robust against adjustment for confounding factors. Investigators noted that uptake of PCV13 was low, at roughly 14%, and those receiving PCV13 within 30 days of testing for pneumonia were excluded to avoid false positives. Overall, the study sample size was low and disease developed in only 3 patients who received PCV13 and therefore meaningful serotype-specific PCV13 efficacy and stratified analyses were not possible.
The 73% effectiveness against the 3.7% of CAP observed here does translate to an estimated rate reduction of people hospitalized for CAP of approximately 62 per 100,000 person-years.
Furthermore, based on average hospitalization length and risk for in-hospital death from CAP, it is possible that up to 824,000 hospital days and 17,440 deaths could be averted over 5 years with widespread adoption of PCV13. Investigators concluded that, “the potential public health benefit of continued PCV13 vaccination in this US population, and in other adult populations globally, remains substantial.”
McLaughlin JM, Jiang Q, Isturiz RE, et al. Effectiveness of 13-valent pneumococcal conjugate vaccine against hospitalization for community-acquired pneumonia in older US adults: a test-negative design [published online May 21, 2018]. Clin Infect Dis. doi: 10.1093/cid/ciy312