Burden of lower respiratory tract infections preventable by adult immunization with 15- and 20-valent pneumococcal conjugate vaccines in the United States

ABSTRACT Background Updated 2022 recommendations indicate all US adults aged ≥65 years and adults aged <65 years with comorbid conditions should receive 15- and 20-valent pneumococcal conjugate vaccines (PCV15/20). We aimed to assess the potential impact of these recommendations on the burden of lower respiratory tract infections (LRTIs) among adults. Methods We estimated the incidence of LRTI cases and associated hospital admissions among enrollees of Kaiser Permanente Southern California health plans from 2016-19. We used a counterfactual inference framework to estimate excess LRTI-associated risk of death up to 180 days after diagnosis. We used prior estimates of PCV13 effectiveness against all-cause and serotype-specific LRTI to model potential direct effects of PCV15/20 by age group and risk status. Results Use of PCV15 and PCV20, respectively, could prevent 89.3 (95% confidence interval: 41.3-131.8) and 108.6 (50.4-159.1) medically-attended LRTI cases per 10,000 person-years; 21.9 (10.1-32.0) and 26.6 (12.4-38.7) hospitalized LRTI cases per 10,000 person-years; and 7.1 (3.3-10.5) and 8.7 (4.0-12.7) excess LRTI-associated deaths per 10,000 person-years. Among at-risk adults aged <65 years not previously prioritized for receipt of PCV13, PCV15 and PCV20, respectively, could prevent 85.7 (39.6-131.5) and 102.7 (47.8-156.7) medically-attended LRTI cases per 10,000 person-years; 5.1 (2.4-8.6) and 6.2 (2.8-10.2) LRTI hospitalizations per 10,000 person-years, and 0.9 (0.4-1.4) and 1.1 (0.5-1.7) excess LRTI-associated deaths per 10,000 person-years. Expansions in serotype coverage, relative to PCV13, accounted for the majority of the expected increase in vaccine-preventable hospitalizations and deaths. Conclusions Our findings suggest recent recommendations including PCV15/20 within adult pneumococcal vaccine series may substantially reduce LRTI burden. Key points Use of PCV15/20 among US adults aged ≥65 years may prevent 521,000-626,000 LRTI cases, 127,000-154,000 hospitalizations, and 50,000-61,000 excess deaths, annually. Updated recommendations for PCV15/20 among adults aged <65 years may prevent 441,000-526,000 LRTI cases, 39,000-46,000 hospitalizations, and 8,000-9,000 deaths annually.