A method for estimating the impact of new vaccine technologies on vaccination coverage rates

Abstract

Vaccines are one of the most cost-effective tools for improving human health and well-being. The impact of a vaccine on population health is partly determined by its coverage rate, the proportion of eligible individuals vaccinated. Coverage rate is a function of the vaccine presentation and the population in which that presentation is deployed. This population includes not only the individuals vaccinated, but also the logistics and healthcare systems responsible for vaccine delivery. Because vaccine coverage rates remain below targets in many settings, vaccine manufacturers and purchasers have a shared interest in better understanding the relationship between vaccine presentation, population characteristics, and coverage rate. While there have been some efforts to describe this relationship, existing research and tools are limited in their ability to quantify coverage rate changes across a broad set of antigens, vaccine presentations, and geographies. In this article, we present a method for estimating the impact of improved vaccine technologies on vaccination coverage rates. It is designed for use with low- and middle-income country vaccination programs. This method uses publicly available data and simple calculations based on probability theory to generate coverage rate values. We first present the conceptual framework and mathematical approach. Using a Microsoft Excel-based implementation, we then apply the method to a vaccine technology in early-stage development: micro-array patch for a measles-rubella vaccine (MR-MAP). Example outputs indicate that a complete switch from the current subcutaneous presentation to MR-MAP in the 73 countries ever eligible for Gavi support would increase overall vaccination coverage by 3.0–4.9 percentage points depending on the final characteristics of the MR-MAP. This change equates to an additional 2.6–4.2 million children vaccinated per year. Our method can be readily extended to other antigens and vaccine technologies to provide quick, low-cost estimates of coverage impact. As vaccine manufacturers and purchasers face increasingly complex decisions, such estimates could facilitate objective comparisons between options and help these decision makers obtain the most value for money.

A model for estimating costs and benefits of new vaccine technologies from the perspective of both buyers and sellers

“…A portfolio selection analysis framework that combines outputs from the CBA and our vaccination coverage method [ 10 ] to identify which combinations of vaccine technologies maximize coverage rate at the lowest total cost.…”

“…Addressing this portfolio selection use case requires a way to estimate the number of doses needed for each vaccine presentation within a given portfolio. To accomplish this, we leveraged our published method [ 10 ] for estimating the impact of vaccine technologies on vaccination coverage rates. This method estimates how well a new vaccine technology addresses known barriers to vaccination such as limited access to cold chain equipment or trained personnel.…”

“…For each permutation: Loop through each country in the analysis, applying our coverage rate estimation methodology [ 10 ] to each successive vaccine presentation to estimate the marginal coverage rate increase attributable to that vaccine. For each vaccine presentation, aggregate demand across all countries by multiplying each country’s target population by the vaccine’s marginal coverage rate for that country.…”

“…Loop through each country in the analysis, applying our coverage rate estimation methodology [ 10 ] to each successive vaccine presentation to estimate the marginal coverage rate increase attributable to that vaccine.…”

“…We achieved this aim in terms of producing an Excel-based model to provide a quantitative financial assessment of a potential investment scenario, both for a single vaccine investment and a portfolio of vaccine investments. We believe this model, which leverages our method for estimating the impact of new vaccine technologies on vaccination coverage rates [ 10 ], would be useful to organizations involved in vaccine investment, manufacturing or purchasing. It may be particularly useful to parties working in vaccine markets that are historically less profitable (e.g., global health donors), including those engaged in VIPS.…”