Evaluating the cost-effectiveness of a sequential pneumococcal vaccination compared to single-dose vaccination strategy for adults in Hong Kong

Abstract

OBJECTIVES: We aimed to assess the cost-effectiveness of a sequential administration of PCV13 followed by PPSV23 compared to a single dose of PPSV23 vaccination for pneumococcal disease control in Hong Kong adults aged ≥65 years and individuals aged 20-64 years with immunocompromizing and chronic conditions. METHODS:: A previously developed deterministic cohort sequential model was applied to compare the outcomes of two vaccination strategies from a societal perspective. Population-specific model input, including incidence, mortality, case-fatality, risk group distribution, vaccination costs, disease management, and productivity loss were estimated from a Hong Kong-wide electronic medical database. Costs were valued in US$ in 2017. Vaccination strategies with an incremental cost-effectiveness ratio (ICER) less than one local GDP per capita ($46,193 in 2017) were defined as highly cost-effective. Deterministic sensitivity analyses (SA) were conducted. RESULTS: The total number of adults included in this model were 6,102,500 (age 20-64, 81.7%; ≥65, 18.3%). At a population level, the sequential vaccination strategy would save $28 million direct medical costs and $4 million indirect costs, over a lifetime for adults aged 20-64 years, in addition to $55 million direct medical costs and $7 million indirect costs for older adults aged ≥65 years. The total additional investment would be $42 million in vaccination costs for the overall population. The sequential administration of PCV13 and PPSV23 was projected to gain 0.004 life years and 0.002 QALY for each individual in all age groups in the base-case analysis. ICER was estimated to be dominant among both age groups. CONCLUSIONS: Compared with single dose PPSV23, sequential vaccination of PCV13 followed by PPSV23 was cost-saving for adults aged ≥20 years. In the deterministic SA, the base-case results were robust for tested parameter uncertainties. Future vaccination policies should consider the cost-effectiveness of a sequential vaccination strategy as a measure to reduce the vaccine-preventable pneumococcal disease burden.