Effectiveness of 13-Valent Pneumococcal Conjugate Vaccine Against Pneumonia Hospitalization Among Medicare Beneficiaries Aged ≥65 in Long-Term Care

Pneumonia causes high rates of hospitalization among adults living in long-term care (LTC) facilities and is a major cause of mortality in this population. Since 2014, pneumococcal conjugate vaccines (PCVs) have been recommended for U.S. adults aged ≥65 years; however, effectiveness of PCVs against all-cause pneumonia hospitalization among adults living in LTC remains unclear. We used Medicare Fee-for-Service claims data to construct an open cohort of beneficiaries aged ≥65 years between September 2014 and December 2019. We estimated 13-valent PCV (PCV13) vaccine effectiveness (VE) by comparing rates of pneumonia hospitalization among PCV13-exposed and PCV13-unexposed time during LTC stays. Discrete-time logistic regression models with generalized estimating equations were used to estimate VE, incorporating time-varying exposures and covariates. Among 3,485,071 beneficiaries meeting the eligibility criteria, the proportion vaccinated with PCV13 increased from 1.1% to 52.7% during the study period. The characteristics of beneficiaries with shorter LTC stays differed from those with longer LTC stays: a lower proportion of beneficiaries aged ≥85 years (LTC stay ≤100 days vs >100 days: 38.5% vs. 48.2%), but a higher proportion with chronic medical conditions (71.4% vs 66.4%), immunocompromising conditions (36.6% vs. 25.2%), and recent hospitalizations (84.1% vs. 74.7%). VE of PCV13-only against all-cause pneumonia hospitalization was 3.8% (95% confidence interval 2.4%-5.2%) overall; 5.6% (3.9%-7.2%) for LTC stays ≤100 days and 0.3% (-2.1%- 2.77%) for LTC stays >100 days. PCV13 reduced the risk of pneumonia hospitalization among this population. Differences in beneficiary characteristics could explain differences in VE by length of LTC stay.