The evolution and distribution of pneumococcal serotypes in adults hospitalized with community acquired pneumonia in Spain using serotype specific urinary antigen detection test: the CAPA study, 2011-2018

Spain introduced 13-valent pneumococcal conjugate vaccine (PCV13) in the childhood national immunization programme (NIP) in 2015-2016 with coverage of three doses of 94.8% in 2018. We assessed the evolution of all pneumococcal, PCV13 vaccine type (VT), and experimental PCV20-VT (PCV13 + serotypes 8, 10A, 11A, 12F, 15B, 22F, 33F) hospitalized community acquired pneumonia (CAP) in adults in Spain from 2011-2018. This was a prospective, observational study of immunocompetent adults (≥18y) admitted to four Spanish hospitals with chest X-ray confirmed CAP between November 2011 and November 2018. Microbiological confirmation was obtained using the Pfizer serotype specific urinary antigen detection tests (UAD1/UAD2), BinaxNow® of urine, and conventional cultures of blood, pleural fluid, and high-quality sputum. Of 3107 adults hospitalized with CAP, 1943 were ≥65 years. Underlying conditions were present in 87% (n=2704) of the study participants. Among all patients, 895 (28.8%) had pneumococcal CAP and 439 (14.1%) had PCV13-VT CAP, decreasing from 17.9% (n=77) to 13.2% (n=68) from 2011-2012 to 2017-2018 (p=0.049). PCV20-VT CAP occurred in 243 (23.8%) of those included in 2016-2018. The most identified serotypes were 3 and 8. Serotype 3 accounted for 6.9% (n=215) of CAP cases, remaining stable during the study period, and was associated with disease severity. PCV13-VT caused a substantial proportion of CAP in Spanish immunocompetent adults eight years after introduction of childhood PCV13 immunization. Improving direct PCV13 coverage of targeted adult populations could further reduce PCV13-VT burden, a benefit that could be increased further if PCV20 is licensed and implemented.