Pneumococcal Vaccination Strategies in 50-Year-Olds to Decrease Racial Disparities: A US Societal Perspective Cost-Effectiveness Analysis

Formulae for calculating subgroup disease burden from overall and reported or assumed relative burden estimates

Background

The risk of disease varies across populations based on factors like age, sex, race, ethnicity, socioeconomic status, and underlying medical conditions. Subgroup or subpopulation data are critical in planning, executing and evaluating public health interventions. However, most studies report the values for the overall (total) population with little or no information on the subgroups. As a result, finding subgroup specific data can be challenging.

Objective

In this report, a set of formulae that can be used to calculate subgroup or subpopulation data using the overall estimates and the reported or assumed relative estimates were derived.

Methods

A simple numerical example was used to illustrate the methodology. Next, symbolic formula for calculating the burden (e.g., incidence, prevalence, or average cost) for 3 (and extended to n number of) subgroups or subpopulations were derived. To account for uncertainty in the data, two statistical methods were used to estimate confidence intervals for the point estimates.

Results

The derived formulae indicated that each subgroup or subpopulation's burden (incidence, prevalence, or average cost) can be calculated as the overall burden adjusted by the ratio of that subgroup or subpopulation's relative burden to the sum of the proportion-weighted relative burden (incidence, prevalence, or average cost) of all the subgroups or subpopulations within the population.

Conclusion

These formulae can help to avoid or minimize potential quantitative and qualitative errors in subgroup or subpopulation disease burden estimates used for health research, interventions and/or policy analyses or deliberations.

Economic evaluation of PCV21 in PCV-naïve adults aged 50-64 years in the United States

OBJECTIVE

In October 2024, the Advisory Committee on Immunization Practices (ACIP) voted to expand the age-based recommendation for pneumococcal vaccination in adults, lowering the youngest age to be vaccinated from 65 to 50 years. This study estimated the incremental health and economic outcomes of age-based use of PCV21 (comparison #1) or PCV20 (comparison #2) versus a previous risk-based recommendation of PCV20 in adults aged 50-64 years in the United States (US).

METHODS

A static multi cohort state-transition Markov model was employed to conduct an economic evaluation from a societal perspective with a lifetime time horizon. Model inputs were obtained or derived from published literature and publicly available databases or reports. Outcomes assessed included undiscounted clinical cases: invasive pneumococcal disease (IPD), inpatient and outpatient non-bacteremic pneumococcal pneumonia (NBPP), post-meningitis sequelae (PMS), deaths from IPD and inpatient NBPP, as well as discounted (at 3 % per year) quality-adjusted life years (QALYs), total cost (in 2023 USD), and the incremental cost-effectiveness ratios (ICERs) reported as $/QALY gained. Probabilistic/Deterministic sensitivity analysis (PSA/DSA) and scenario analysis were conducted.

RESULTS

In all pairwise comparisons, PCV21 (comparison #1) showed a reduction in clinical cases and significantly lower ICERs, at least ten times lower than those observed with PCV20 (comparison #2). The ICER for comparison #1 was $73,000 (95 % uncertainty interval (UI): $40,000, $134,000) per QALY gained. In scenario analyses, the ICER ranged from cost-saving to $80,000/QALY gained. In contrast, the ICER for comparison #2 was $820,000 (95% UI: $572,000, $1.4 million)/QALY gained and varying from $290,000 to $1.0 million/QALY gained in scenario analyses.

CONCLUSIONS

An age-based vaccination strategy for adults aged 50-64 years in the US can lead to reductions in pneumococcal disease cases and associated mortality compared to a risk-based strategy. Moreover, PCV21 was a more effective and economically favorable option than PCV20 across a wide range of scenarios and input values.

Systematic literature review of cost-effectiveness analyses of adult 15- and 20-valent pneumococcal vaccines

BACKGROUND

The economic and public health benefits of adult pneumococcal vaccines vary across countries due to different epidemiology and costs. We systematically reviewed and summarized findings and assumptions of cost-effectiveness analyses (CEA) of the recently introduced 15- and 20-valent pneumococcal conjugate vaccines (PCV15 and PCV20) in adults.

METHODS

We performed a systematic search for CEA studies of PCV15 and/or PCV20 versus existing strategies via PubMed, EMBASE, CEA Registry, EconLit, HTA Database, and NITAG resource center through April 23, 2024. Study characteristics, methods, assumptions, and findings were extracted independently by two reviewers; quality was assessed using ECOBIAS. Results were synthesized qualitatively to summarize key attributes and conclusions.

RESULTS

Of 137 identified records, 26 studies were included; the majority (24/26) concerned high-income countries. All employed static Markov-type models comparing higher-valent PCVs used alone or in combination with 23-valent pneumococcal polysaccharide vaccine (PPSV23) to current recommendations (PPSV23 alone, PCV13 alone, PCV13 + PPSV23, no vaccination). Most studies (22/26) concluded PCV20 used alone was cost-saving (dominant) or cost-effective compared to other adult pneumococcal strategies (PPSV23 alone, PCV13 ± PPSV23, PCV15 ± PPSV23, or no vaccination). PCVs were generally assumed to have serotype-specific effectiveness equal to PCV13 efficacy in the pivotal trial, though four studies used estimates from a Delphi panel; protection was assumed to last between 10 and 20 years. PPSV23 was assumed to have lower effectiveness against non-bacteremic pneumonia and shorter duration of protection. Herd effects from higher-valent PCVs in childhood (12/26), serotype replacement (2/26), or both (1/26) were included in half (13/26) of studies, which attenuated adult vaccine impact. Most studies were assessed as low risk of bias; five abstracts did not provide sufficient information for assessment.

CONCLUSION

Current evidence indicates that 20-valent PCV used alone is likely to be cost-effective or dominate other adult pneumococcal strategies. Future research is needed to address remaining uncertainties in assumptions and to support evidence-based policymaking.

Cost-effectiveness of an in-development adult-formulated 21-valent pneumococcal conjugate vaccine in US adults aged 50 years or older

Indirect effects of childhood pneumococcal conjugate vaccines (PCV) have diminished the cost-effectiveness of current adult vaccine recommendations. An in-development adult-formulated 21-valent pneumococcal conjugate vaccine (PCV21) may play a critical role in reducing pneumococcal illness by targeting a larger number of serotypes responsible for adult pneumococcal infections. This study assesses the cost-effectiveness of PCV21 in US adults aged 50 years or older compared with currently recommended pneumococcal vaccines, from both the societal and healthcare perspectives. A Markov model evaluated the lifetime cost-effectiveness of PCV21 (given at age 50 years only, at ages 50/65 years, and risk-based at ages < 65 years plus age-based at age 65 years) compared to no vaccination and to currently recommended pneumococcal vaccines given either as currently recommended or routinely at ages 50/65 years. The analysis was conducted in hypothetical Black and non-Black cohorts aged 50 years or older, with and without considering childhood pneumococcal vaccination indirect effects. Model parameters were based on US data. Parameter uncertainty was assessed using 1-way and probabilistic sensitivity analyses. From the societal perspective, PCV21 at ages 50/65 years compared to PCV21 at age 50 years cost $7,410 per quality adjusted life year (QALY) gained in Black cohort analyses and $85,696/QALY gained in the non-Black cohort; PCV21 at ages 50/65 years had the most favorable public health outcomes. From the healthcare perspective, compared to no vaccination, PCV21 at age 50 years cost $46,213/QALY gained in the Black cohort and $86,629/QALY in non-Blacks. All other strategies were dominated in both cohorts and from both perspectives. When considering childhood pneumococcal vaccination indirect effects, costs of PCV21 at ages 50/65 years remained less than $140,000/QALY gained from the societal perspective in both populations. PCV21 is potentially cost-effective compared to currently approved pneumococcal vaccines in adults aged 50 years or older from both the societal and healthcare perspectives.