Purpose: The effectiveness and cost-effectiveness of 13-valent pneumococcal conjugate vaccine (PCV13) compared with the currently recommended 23-valent pneumococcal polysaccharide vaccine (PPSV) in adults is unclear. Adult PCV13 could prevent more disease than PPSV, if adult studies show (as shown in children) effectiveness against noninvasive pneumococcal pneumonia (NPP), the commonest cause of pneumococcal disease hospitalization; no consistent evidence of PPSV effectiveness against NPP exists. However, PCV13 covers fewer serotypes causing the more severe invasive pneumococcal disease (IPD), and future indirect effects from routine pediatric PCV13 use may further reduce its coverage among adults.
Methods: We used a Markov model to estimate the cost-effectiveness of pneumococcal vaccination strategies in 50-year-old cohorts over their lifetime. Strategies were chosen by a Delphi expert panel, who also estimated age- and comorbidity-specific vaccine effectiveness. Sources for parameters included CDC’s Active Bacterial Core surveillance data, as well as National Health Interview Survey, National Hospital Discharge Survey, National Inpatient Sample, Framingham Study, and SEER data. We also projected changes in adult pneumococcal serotype epidemiology and disease rates due to indirect effects from childhood PCV13. Utilities were obtained from the literature. We took a societal perspective, discounting costs and effectiveness 3%/yr.
Results: In the base case, using observed age- and comorbidity-based PPSV uptake, PCV13 given as a substitute for PPSV in the current recommendations (i.e., vaccination at age 65 years and at younger ages if comorbidities are present) cost $28,900/QALY gained compared with no vaccination. PCV13 given routinely at ages 50 and 65 years cost $45,100/QALY compared with the PCV13 substituted in current recommendations strategy. A strategy of PCV13 at ages 50 and 65 then PPSV at age 75 gains 0.00002 more QALYs, costing $496,000/QALY gained. Two other strategies were dominated. Results were robust in sensitivity analysis and alternative scenarios, except when PCV13 effectiveness against NPP was assumed to be low. Here, PPSV use as currently recommended was favored, costing $34,600/QALY, and PCV13 substituted in current recommendations cost $131,000/QALY gained.
Conclusions: The analysis supports vaccinating adults with PCV13 rather than PPSV, but is sensitive to variation of NPP prevention assumptions. Changing current pneumococcal vaccination recommendations may require evidence of PCV13 effectiveness against NPP from ongoing clinical trials and await data availability on the indirect effects of childhood PCV13.