Exploratory efficacy endpoints in the Community-Acquired Pneumonia Immunization Trial in Adults (CAPiTA)

Abstract

Background: The Community-Acquired Pneumonia Immunization Trial in Adults (CAPiTA) assessed vaccine-type community-acquired pneumonia (VT-CAP) and vaccine-type invasive pneumococcal disease (VT-IPD) prevention with 13-valent pneumococcal conjugate vaccine (PCV13) in adults aged ⩾65years. We report vaccine efficacy (VE) of PCV13 for the remaining 23 exploratory endpoints and serotype distributions for pneumococcal CAP and IPD.

Methods: This was a parallel-group, randomised, placebo-controlled, double-blind trial comparing single-dose PCV13 with placebo. Exploratory CAP endpoints included first episode of confirmed non-VT (NVT) pneumococcal CAP; all confirmed episodes of NVT pneumococcal CAP, pneumococcal CAP, nonbacteraemic/noninvasive (NB/NI) VT pneumococcal CAP, and NB/NI pneumococcal CAP; and first and all episodes of culture-confirmed VT pneumococcal CAP, culture-confirmed pneumococcal CAP, culture-confirmed NVT pneumococcal CAP, probable VT pneumococcal CAP, probable NVT pneumococcal CAP, and probable and possible pneumococcal CAP. Exploratory IPD endpoints included all episodes of VT-IPD and IPD, and first and all episodes of NVT-IPD. The per-protocol and modified intent-to-treat (mITT) populations were evaluated.

Results: In total, 84,496 participants were enrolled. Eight of 23 exploratory CAP and IPD endpoints were statistically significant in both populations. In the per-protocol population, these included VE of 29% for all episodes of confirmed pneumococcal CAP, 43% for all NB/NI episodes of VT pneumococcal CAP, 52% for all episodes of culture-confirmed pneumococcal CAP, and 53% for all episodes of IPD. Comparable VE estimates were observed in the mITT population. The most common VT serotypes were 1 (10 first episodes of confirmed pneumococcal CAP; 2 first episodes of IPD) and 7F (22; 7) among PCV13 and placebo recipients, respectively.

Conclusions: The results of this analysis yielded statistically significant PCV13 VE for all episodes of confirmed pneumococcal CAP (including NB/NI and culture-confirmed episodes) and for all episodes of IPD in adults aged ⩾65years. These findings are consistent with the primary efficacy analysis. ClinicalTrials.gov identifier: NCT00744263.

Keywords: Adult; Community-acquired pneumonia; Invasive pneumococcal disease; PCV13; Pneumococcal conjugate vaccine; Vaccine efficacy.