Effects of 13-valent pneumococcal conjugate vaccination of adults on lower respiratory tract infections and antibiotic use in primary care: secondary analysis of a double-blind randomized placebo-controlled study

Objectives: The efficacy of 13-valent pneumococcal conjugate vaccine (PCV13) in adults to prevent community-acquired pneumonia (CAP) and lower respiratory tract infections (LRTI) not requiring hospitalization is unknown. We determined the effect of PCV13 on CAP, LRTI and antibiotic use in the primary care setting. Methods: Community-dwelling immunocompetent adults over 65 years of age were randomized to PCV13 or placebo as part of the double-blind Community-Acquired Pneumonia immunization Trial in Adults (CAPiTA). CAP and LRTI episodes and antibiotic prescription data were extracted from general practitioner information systems of 40 426 individuals. Vaccine efficacy (VE) of PCV13 was determined using Poisson regression with robust standard errors, comparing CAP and non-CAP LRTI episodes, LRTI-specific and total antibiotic prescriptions. Results: In all, 20 195 participants received PCV13 and 20 231 received placebo. A total of 1564 and 1659 CAP episodes occurred in the PCV13 and placebo group, respectively; VE 5.5% (95% CI –2.6% to 13.0%). Non-CAP LRTI episodes occurred 7535 and 7817 times in the PCV13 and placebo groups, respectively; VE 3.4% (95% CI –2.0% to 8.5%). A total of 8835 and 9245 LRTI-related antibiotic courses were prescribed in the PCV13 and placebo arms, respectively; VE 4.2% (95% CI –1.0% to 9.1%). Antibiotic courses for any indication were prescribed 43 386 and 43 309 times, respectively; VE –0.4% (–4.9% to 3.9%). Conclusions: PCV13 vaccination in the elderly is unlikely to cause a relevant reduction in the incidence of CAP, LRTI, LRTI-related antibiotic use or total antibiotic use in primary care.