Effectiveness of Pneumococcal Vaccination Against Pneumococcal Pneumonia Hospitalization in Older Adults: A Prospective, Test-Negative Study

[[[ Background: ]]] Despite use of the 13-valent pneumococcal conjugate vaccine (PCV13) and 23-valent pneumococcal polysaccharide vaccine (PPSV23) over the last decade, the disease burden of pneumococcal pneumonia is still high. We evaluated the field effectiveness of PCV13, PPSV23, and sequential vaccination against pneumococcal pneumonia in older adults. [[[ Methods: ]]] This prospective multicenter study was conducted in adults aged ≥65 years hospitalized with community-acquired pneumonia (CAP) between September 2015 and August 2017. The case-control test-negative design was used to estimate vaccine effectiveness (VE) against pneumococcal CAP. [[[ Results: ]]] Of 1525 cases with CAP hospitalization, 167 (11.0%) were identified as pneumococcal CAP. In the elderly aged ≥65 years, the adjusted VE of pneumococcal vaccines against pneumococcal CAP was statistically insignificant: 40.0% (95% confidence interval [CI], -10.8% to 67.5%) for PCV13 and 11.0% (95% CI, -26.4% to 37.3%) for PPSV23. However, in the younger subgroup (aged 65-74 years), sequential PCV13/PPSV23 vaccination showed the highest adjusted VE of 80.3% (95% CI, 15.9%-95.4%), followed by single-dose PCV13 (adjusted VE, 66.4% [95% CI, .8%-88.6%]) and PPSV23 (adjusted VE, 18.5% [95% CI, -38.6% to 52.0%]). [[[ Conclusions: ]]] Sequential PCV13/PPSV23 vaccination is most effective for preventing pneumococcal CAP among the elderly aged 65-74 years.