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Johns Hopkins Bloomberg School of Public Health


Keyword: dvi

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.

By Rebecca Van Roy, Communications Officer, Vaccine Advocacy and Education at Sabin Vaccine Institute

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) 

Earlier this year, DVI convened the Americas Dengue Prevention Board along with scientists, global health experts, mathematical modelers and representatives of dengue vaccine manufacturers to discuss updates in dengue vaccines and vaccine introduction. Held in Bogota at the Colombian National Institute of Health (Institituto Nacional de Salud – INS), the meeting was instrumental given the new available clinical trial data, particularly the results of the first Phase 3 trials ever completed for a dengue vaccine candidate. These results demonstrated that a safe and effective dengue vaccine is feasible

A mosquito that costs over $2 billion

Dengue, caused by a small mosquito with black and white striped legs, is the most widespread vector-borne disease in the Americas. In 2013, cases and deaths nearly doubled those of previous years in the region. The southern cone reported the highest incidence rate of cases, but the Andean region reported the highest number of severe cases. The burden of dengue in the Americas has been estimated at more than $2 billion dollars, from hospitalization costs to loss of productivity, representing a significant threat to the wellbeing of the region.

A safe and effective vaccine can help reduce this threat. While the decision to introduce a dengue vaccine can only be driven at the country level, such decisions must be based on sound evidence. DVI Dengue Prevention Board Meetings seek to share and update existing dengue knowledge and identify gaps to ensure countries have scientific, objective data to make informed public health decisions proactively, before a vaccine becomes available.

An open forum to share dengue knowledge –-and its gaps

With this objective in mind, the meeting offered an open forum where participants revisited the minimum requirements for successfully launching a dengue vaccination program among other crucial dengue topics.

On the first day, they reviewed the status of dengue vaccine development with representatives of the manufacturers of the five vaccines in clinical trial (Butantan/NIH, GSK/Fiocruz/Walter Reed, Merck, Sanofi Pasteur and Takeda). They also discussed the applications of mathematical modeling for predicting the impacts of dengue vaccination.

On the second day, country representatives presented the current dengue situation in their homeland and perspectives on dengue vaccine introduction and use.

Finally, the meeting broke into groups to assess considerations for vaccine introduction. The Board then met separately to draw conclusions. The meeting ended with the closing remarks of the Colombian Ministry of Health, who highlighted the spread of dengue and the urgent need to stop it. 

Board Conclusions

The Board noted the critical importance of linked disease surveillance and vaccination registries to monitor coverage and vaccine effectiveness, as well as monitoring for vaccine safety. They also urged the standardization of age groups and case definitions of dengue disease across countries in the region to enable comparisons. They called for further analyses to understand how a limited supply of vaccine might best be utilized in the first year(s) of vaccine introduction. They affirmed the importance of the Pan-American Health Organization (PAHO) for supporting vaccine introductions, particularly through activities such as issuing recommendations for laboratory-based disease surveillance in the region, with an aim of standardizing the diagnostic tests.

The table below summarizes these conclusions. For more detail we encourage you to read the full report here: “Development of Dengue Vaccines: A Review of the Status and Future Considerations.


About Dengue Prevention Boards

In 2007, PDVI (Pediatric Dengue Vaccine Initiative—DVI’s precursor) established two regional Dengue Prevention Boards (DPBs) — one for Asia and one for the Americas. Members of the boards include medical and public health experts, opinion leaders and policy makers from countries in their respective regions. They meet once a year to advise on dengue surveillance, diagnostics, vaccine introduction and communications.

All reports on DPB meetings are published in the DVI website to inform dengue and global health stakeholders.