Effectiveness of 13-valent pneumococcal conjugate vaccine against vaccine-type invasive pneumococcal disease in older adults

In 2014, the Advisory Committee on Immunization Practices recommended routine use of the 13-valent pneumococcal conjugate vaccine (PCV13) in adults age ≥ 65 years. Incidence of most PCV13-serotype cases declined, however serotype 3 cases have persisted. We estimated PCV13 vaccine effectiveness (VE) against PCV13-serotypes and serotype 3 invasive pneumococcal disease (IPD) among Kaiser Permanente Northern California (KPNC) adults. This observational study included adults ≥65 years between September 1, 2014-December 31, 2020. We used active laboratory-based surveillance to identify and serotype all Streptococcus pneumoniae isolates obtained from normally-sterile sites. We estimated the odds ratio (OR) of vaccine-type IPD using conditional logistic regression stratified by age and calendar day, adjusting for sex, age, race, ethnicity, influenza vaccine receipt, 23-valent pneumococcal polysaccharide vaccine receipt since age 65, pneumonia risk factors, healthcare utilization, and KPNC service area. We estimated VEAdjusted as (1-ORAdjusted) × 100 %. There were 610,576 adults ≥65 years in the study population. By the end of the study period, PCV13 coverage was nearly 80 %. There were 307 IPD cases during the study period, of which 98 (31.9 %) were serotype 3. PCV13 was associated with a VEAdjusted of 61.5 % (95 % CI: 36.2, 76.7; p