Q&A: Understanding the Link Between Tech, Vaccine Coverage

Monday, June 13, 2022

Pascale Leroueil headshot 2021


with Pascale Leroueil, WDI Vice President for Healthcare 

As the pandemic has revealed, vaccine coverage in low- and middle-income countries is well below that of higher-income countries. And while global attention tends to focus on a vaccine’s efficacy through R&D and clinical trials, there is less understanding about what factors lead to people ultimately receiving a vaccination. This knowledge discrepancy led WDI Healthcare Vice President Pascale Leroueil and fellow researchers to hone in on the role a particular technology may have in the overall success of a vaccine in terms of population coverage. This can include factors such as how vaccines are administered (needles versus orally administered vaccines, for example), and cold-storage supply chains. In a recent study, Leroueil and co-authors present a method for estimating the impact of vaccine technologies on vaccination coverage rates. They designed the method to help decision makers better assess the most value for their money, with the goal of improving vaccine coverage for vulnerable communities.

What led you and your colleagues to develop this methodology? 

We wanted to help donors think about the potential impact of their research, manufacturing and deployment decisions related to vaccines. The wonderful thing about research and product development is that the options of where to invest are nearly endless. But money and time aren’t endless, even for donors. We had been asked by a global donor to help them think about the relationship between a given vaccine technology and its associated vaccination coverage rate. For example, if countries had access to a microarray, patch-based vaccine delivery system that could replace the standard syringe and needle delivery system, what might that do to vaccination coverage rates across the world? As a first approximation you might answer, “not much.” However, if you start to think about the operational implications of what it means to move from something that requires a mid-level skilled healthcare worker such as a nurse to a less skilled healthcare worker such as a community health worker, then you can start to see how changing the delivery system could lead to higher vaccination coverage rates. We thought an approach that could quantify the potential vaccination coverage rates that could be achieved with different vaccine presentations would be useful to many types of stakeholders, including donors, manufacturers and country-level decision makers.  

Can you describe what methodology works in layman's terms?

We started with the assumption that vaccination coverage rates are a function of two things: (a) the barriers to vaccination in a given environment and (b) the characteristics of the vaccine presentation. As I alluded to earlier, some vaccine technologies could mitigate or remove some barriers in some contexts. For example, one barrier in a given context might be lack of refrigeration. Therefore, a vaccine that doesn’t require refrigeration would remove this barrier to vaccination for the people in this context. We ended up defining six barriers to vaccination that we felt could be overcome by changing the vaccine presentation, or how it’s administered to a patient.  From there, we had to think about how we would turn our relatively simple assumption into numbers that would allow us to say something to the effect of, “If Country X had access to Vaccine Presentation Y, they could achieve a vaccination coverage of Z%.” We turned to something called, “probability theory,” which is something you likely learned in middle school. Basically, it says if the probability of A happening is a, and the probability of B happening is b, the probability of both A and B happening is a x b. The math we used is slightly more complicated, but the general idea is the same. Namely, the probability of a person in Country X with access to Vaccine Presentation getting vaccinated is the product of the probabilities of a person overcoming each of the six barriers we defined. 

One of the neat things about our approach is that it can be used at any point along the vaccine development pathway. From someone thinking about research & development to someone considering vaccines, this approach allows them to estimate the maximum demand for a particular vaccine presentation.

How would a vaccine manufacturer utilize it in decision making?

The quick answer is that it could help vaccine manufacturers forecast potential demand for a particular vaccine presentation. Vaccine manufacturing is a complex and expensive business that relies heavily on scale to make it work. Realistically, a manufacturer needs to have a pretty good understanding of how many vaccines they will be able to sell and at what price before they decide to start manufacturing. This approach allows them to understand the former, while another approach we are developing allows them to understand the latter.

How about donor organizations or ministries of health? 

Donor organizations in the vaccine-related space would use this approach to guide their investments, whether that’s at the research and development stage, or manufacturing stage. For example, say a donor has five vaccine presentations in the pipeline, all against the same disease. Now say they want to move only two of those vaccine presentations forward. How do they make the decision about which vaccine presentations to move forward? While there are probably a few parameters that go into that decision making process, one of them is most certainly the potential vaccination coverage that each of the vaccine presentations could yield. In many ways, the Ministries of Health are making similar decisions—for a given disease, which vaccine presentation should the country purchase? Again, there are likely a few parameters that go into that decision making process but one of them is most certainly the potential vaccination coverage.

Could this methodology be applied to other types of vaccine technologies, or perhaps future technologies?

Absolutely. The approach we outlined in the paper can be used as-is for any vaccine-related technology. In principle, one could extend this approach to almost any product or service, whether it is health-related or not. What would need to change is the ‘barriers.’ For example, if we’re talking about an ultrasound, access to refrigeration is probably not a barrier to treatment but access to power probably is a barrier to treatment. Although vaccines are near and dear to our heart, we intentionally developed an approach that could be adapted to other products or services.

What has the pandemic revealed in terms of vaccine coverage that this research might address?

The importance of considering the contexts in which a vaccine presentation will be deployed. I want to be clear and say what was done in terms of vaccine development, manufacturing and deployment was nothing short of a miracle. Having said that, the pandemic shined a huge spotlight on the barriers to vaccination that exist for many people across the world. The refrigeration requirements for some of the presentations were a significant barrier in many countries, as was the need for multiple doses and access to skilled health workers. The result? Staggering levels of Covid-19 vaccine inequity. That vaccine inequity would exist at all is terrible, but that it still exists is unforgivable. Those with resources in the vaccine space should be actively developing more platforms that help reduce the barriers to vaccination for those with the fewest resources. Although our approach could help decision makers estimate the potential impact of doing this, I can only hope it’s now self-evident that identifying ways to address these barriers before the next pandemic is critical to our survival. 

About WDI

At the William Davidson Institute at the University of Michigan, unlocking the power of business to provide lasting economic and social prosperity in low- and middle-income countries (LMICs) is in our DNA. We gather the data, develop new models, test concepts and collaborate with partners to find real solutions that lead to new opportunities. This is what we mean by Solving for Business — our calling since the Institute was first founded as an independent nonprofit educational organization in 1992. We believe societies that empower individuals with the tools and skills to excel in business, in turn generate both economic growth and social freedom — or the agency necessary for people to thrive.

WDI’s Education team works with world-class instructors from leading universities — including our home at the University of Michigan — to develop and deliver programs. Through our rich faculty network, cultivated over the past 25+ years, we deploy experts with both deep subject matter expertise and relevant regional experience. 

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