Effectiveness of 23-Valent Pneumococcal Polysaccharide Vaccine against Invasive Pneumococcal Disease in Adults, Japan, 2013-2017

Abstract

The decline in the proportion of pneumococcal conjugate vaccine (PCV)-covered serotypes among adult invasive pneumococcal disease (IPD) patients might change the overall effectiveness of the 23-valent pneumococcal polysaccharide vaccine (PPSV23) because its effectiveness differs according to serotype. Using the indirect cohort method, we calculated the effectiveness of PPSV23 against IPD among adults in Japan to assess the impact of the national pediatric PCV program. Clinical and epidemiologic information and pneumococcal isolates were collected from IPD patients >20 years of age through enhanced IPD surveillance during April 2013-December 2017. Adjusted effectiveness against PPSV23-serotype IPD was 42.2%. Despite a substantial decline in the proportion of 13-valent PCV serotypes during the study period (45% to 31%), the change in effectiveness for PPSV23-serotype IPD was limited (47.1% to 39.3%) and only marginal in the elderly population (39.9% to 39.4%). The pediatric PCV program had limited impact on PPSV23 effectiveness against IPD in adults.

Keywords: 23-valent pneumococcal polysaccharide vaccine; IPD; Japan; PPSV23; indirect cohort method; indirect effect; invasive pneumococcal disease; respiratory diseases; vaccine effectiveness; vaccine-preventable diseases.

Figure

Percentage of vaccine-covered serotypes among pneumococcal isolates from 1,108 invasive pneumococcal disease patients >20 years of age, stratified by year and age group, Japan, 2013–2017. NVT, non–vaccine type; PCV7, 7-valent pneumococcal conjugate vaccine; PCV13, 13-valent pneumococcal conjugate vaccine; PPSV23, 23-valent pneumococcal polysaccharide vaccine.