By Dagna Constenla, Gatien de Broucker, Jorge Martin del Campo and Alexandra Greenberg, IVAC at Johns Hopkins University

This article was originally published on the Dengue Vaccine Initiative's blog and is cross-posted here with permission. IVAC is a member of the Dengue Vaccine Initiative (DVI). 

The successful introduction of a vaccine in affected countries depends heavily on issues such as supply constraints, potential demand, and the impact of policy decisions on future demand and supply. Strategic demand forecasts (SDFs) play a central role in enabling vaccine suppliers, donors, and country-level stakeholders to make informed decisions about vaccine supply, financing, and adoption. In recent years, Accelerated Development and Introduction Plans (ADIPs) have used strategic demand forecasts to adjust market forces for the purpose of accelerating access to new vaccines in countries where they are needed the most.

Our team at the International Vaccine Access Center at Johns Hopkins University has developed several models to estimate the potential demand of dengue vaccine and the costs associated with dengue introduction programs, enabling vaccine suppliers, donors, and country-level stakeholders to make informed decisions about vaccine supply, financing, and adoption. These models have been developed with specific price and coverage assumptions for a variety of target ages and regions.

For the next phase of our project, we will quantify the potential demand for dengue vaccines in Latin America, specifically Mexico, Colombia, Honduras, Paraguay, El Salvador and Peru, taking into account the different scenarios envisioned by each country. Using advanced economic modeling, we aim to determine which factors would drive dengue vaccine demand in these countries.

Building off of our team’s current work on a similar model in Brazil, our team will develop SDF models in collaboration with the Ministries of Health in Mexico, Colombia, Honduras, Paraguay, El Salvador and Peru. While we already have access to relevant information in some of the countries in the region, this collaborative work is essential to ensure that the outputs of the model are relevant and integrated in the decision-making process for each country of interest.

Approaching six different countries at the same time brings many challenges in forecasting the potential demand of the vaccine. Each country has unique characteristics that impact the way vaccine introduction decisions are made. Differing geographical specificities, population demographics, health systems and political infrastructure within countries are good examples.

While strategic demand forecasts can be powerful communication tools, they have certain limitations. SDF depends on the availability of vital pieces of information from stakeholders, namely in-country policy makers, industry, and global donors. Getting information from one stakeholder can be hard without the ability to rely on credible information from other relevant players. All stakeholders must participate with equal commitment towards providing timely and accurate data for the results of strategic demand forecasts to be valid. The lack of reliable information can also make it difficult to verify or test key assumptions made by disease modelers.

In addition to the potential absence of consistent and reliable information, it can be challenging to generalize across developing countries. Significant differences in low- and middle-income countries can make operating conditions vastly divergent on the ground, thereby making broad-based assumptions and generalizations ineffective. Economic and political conditions – such as the unequal distribution of resources and infrastructure, limited budgets, inadequate healthcare policies, and divergent political priorities – can vary substantially between countries, even within the same sub-region.

Lastly, unequal financial commitment from international and local donors makes it difficult to determine the price funders would be willing and able to pay for a vaccine. This is an especially crucial piece of information for low-income countries, which would be unable to introduce a new vaccine without significant support from outside funders. Without this vital information it is challenging to estimate the potential demand for a vaccine in any given market.

So far we are having fruitful discussions with highly positioned local stakeholders in each country including program heads, government officials and representatives at the national and state levels. Their response has surpassed our expectations: they are themselves working to engage new key actors in this discussion. Stakeholders are driven and committed to understanding this disease and to ensuring that a vaccine is introduced in the most efficient and beneficial way for every country.

This research will be critical for laying the groundwork so that countries in the Americas can establish a viable vaccine introduction plan, which can be immediately implemented following the introduction of a dengue vaccine.