OBJECTIVES: The changing serotype distribution of pneumococcal disease in the older population since the introduction of PCV13 in infants has led to a renewed interest in the value of PPV23 vaccine. This study assessed the cost-effectiveness of revaccinating adults aged 65 years or above with PPV23 after 5 years, when compared to a single dose of PPV23.

METHODS: A population-based Markov model was developed based on five health states including no pneumococcal disease, invasive pneumococcal disease (IPD), non-bacteremic pneumococcal pneumonia (NBPP), post-meningitis sequelae and death. Adults aged 65 years or above in the UK were followed up to 100 years of age or until death, if earlier. Vaccine efficacy against IPD was based on a meta-analysis and a clinical trial. Vaccine efficacy against NBPP was based on a population-based cohort study and a clinical trial. Cost and utility were discounted at a rate of 3.5% annually. The main outcome estimated was the incremental cost-effectiveness ratio (ICER), expressed as additional cost per quality-adjusted life year (QALY) gained . A threshold of £20,000 was considered cost-effectiveness. Sensitivity analyses were conducted to test the robustness of the result.

RESULTS: In the base case analysis, compared to single dose vaccination with PPV23, discounted incremental costs and incremental QALYs gained for revaccination with PPV23 were estimated at £99 million and 6,364, respectively, corresponding to an ICER of £15,506/QALY.

CONCLUSIONS: Revaccinating adults aged 65+ years with PPV23 in the UK was estimated to be a cost-effective vaccination strategy as compared to vaccinating with a single dose of PPV23.