Introduction
Pneumococcal disease (PD) poses a significant health threat, particularly among adults aged ≥50 years. This illness, caused by Streptococcus pneumoniae bacteria, encompasses invasive PD (IPD) and non-IPD (which includes non-bacterial pneumococcal pneumonia [NBP]), with varying incidence rates across age groups. However, PD incidence is highest in individuals over 65 years of age, with an associated mortality of 8.1%. Preventing PD in Japan is especially crucial, considering that almost 30% of their population is elderly.
Current Pneumococcal Disease Vaccination Landscape
As of January 2024, Japan offers three vaccines against PD: the 23-valent pneumococcal polysaccharide vaccine (PPSV23), along with the 13- and 15-valent pneumococcal conjugate vaccines (PCV13 and PCV15). While PPSV23 is part of the national immunisation program for specific age groups and at-risk individuals, concerns persist regarding its efficacy, as evidenced by sustained rates of IPD caused by PPSV23-serotypes and a high IPD incidence rate of 47% in adults.
Advancements in Vaccination Strategies
Unlike traditional vaccines like PPSV23, newer conjugate vaccines such as PCV13 and PCV15 offer enhanced immune responses, leading to long-term protection through the production of memory B cells. The forthcoming 20-valent pneumococcal conjugate vaccine (PCV20) shows promising results in trials, boasting improved immune responses and potential to mitigate IPD and non-bacteremic pneumococcal pneumonia cases, particularly among vulnerable populations.
Economic Evaluation and Cost-Effectiveness of PCV20
Recent studies, including one by Hoshi et al., highlight the cost-effectiveness of PCV20, especially in elderly populations. The current study investigated the cost-effectiveness of PCV20 compared to PPSV23 in adults >65 years and high risk adults >60 years, from a payer and societal perspective. The analysis indicates that PCV20 emerges as a dominant and cost-effective strategy. At a cost effectiveness threshold of JPY5,000,000 per QALY, the incremental net monetary benefit (INMB) was JPY30,205 and JPY8,170 using a societal and payer perspective, respectively. Compared to PPSV23, PCV20 reduced numbers of bacteremia, meningitis, and inpatient and outpatient cases of NBP. Modelling also revealed that PCV20 can reduce medical costs and productivity loss by JPY2.84 billion and JPY34.01 billion, respectively – this offsets vaccination costs of JPY2.10 billion.
Figure 1. Probabilistic sensitivity analysis results for the cost-effectiveness plane (PCV20 vs PPSV23). PCV20: 20-valent pneumococcal vaccine; PPSV23: 23-valent pneumococcal polysaccharide vaccine; QALY: quality-adjusted life year. The red line corresponds to the cost-effectiveness threshold of JPY5,000,000 per QALY gained used in this analysis.
Navigating Pandemic Impacts and Future Prospects
The COVID-19 pandemic inadvertently led to a reduction in PD incidence rates, underscoring the importance of preventive measures. Looking ahead, the potential approval of PCV20 for pediatric use in Japan could further bolster disease prevention efforts, leveraging herd immunity benefits and potentially reshaping disease epidemiology.
Conclusion
In conclusion, the introduction of PCV20 in Japan holds immense promise in combating PD, offering a cost-effective and more efficacious alternative to existing vaccines. With its potential to reduce healthcare burdens and improve outcomes for at-risk populations, PCV20 signifies a significant advancement in preventive healthcare strategies against pneumococcal disease.
