Highly Extensible Resource for Modeling Event-Driven Supply Chains (HERMES)

Funded by the Bill & Melinda Gates Foundation, HERMES (Highly Extensible Resource for Modeling Event-Driven Supply Chains) is a software program that allows users to generate a detailed computer simulation model of a supply chain. The Global Obesity Prevention Center (GOPC) at Johns Hopkins University and the Pittsburgh Supercomputing Center (PSC) designed the first version of HERMES to help evaluate and improve vaccine supply chains throughout the world.

The model can serve as a “virtual laboratory” for users to evaluate a supply chain and test the effects of implementing different potential policies, interventions, practices and technology changes.

So far, HERMES has been utilized to create models of multiple countries’ vaccine supply chains in Africa (Niger, Benin, Senegal, Chad, Kenya, and Mozambique) and Asia (Thailand, Vietnam, and India) to help decision makers better understand the complexities involved.

Major organizations such as UNICEF, GAVI, Clinton Health Access Initiative, Doctors Without Borders (MSF) and PATH have used HERMES to guide vaccine supply chain decision making. For example, in 2012, the HERMES team worked with the Agence de Médecine Préventive (AMP) and WHO to help the Benin Ministry of Health determine whether the Benin vaccine supply chain was ready for the rotavirus (most common cause of diarrheal disease among infants and young children) and meningococcal (meningitis) vaccines and if they should simply add more refrigerators and vehicles or significantly redesign their vaccine supply chain. Using HERMES to explore the different options, the team helped the Benin Ministry of health identify a new design that would consolidate storage locations, remove a supply chain level and replace point-to-point motorbike routes with truck shipping loops. This new design could not only increase the number of vaccines successfully delivered and thus save lives, but also save more than $500,000 over the course of 5 years.

In 2015, the GOPC and PSC team used HERMES to help VillageReach simulate the possible value of using Unmanned Aerial Vehicles (UAVs), also known as drones, to transport vaccines in Mozambique.  The simulation results showed the potential value of such drones and informed the debate of their possible use in delivering health commodities. The work showed the value of such drones and helped paved the way for their use in delivering vaccines.

In 2016, the HERMES Team partnered with MSF to model the economic and clinical impacts of heat-stable vaccines in various countries. The study showed that that not only could vaccines that don’t require refrigeration help increase vaccination rates in these countries, the cost savings of decreased cold chain utilization and improved health outcomes could more than cover the costs of heat-stable vaccines at double or triple the price.


HERMES software is now open-sourced, readily available to the public. You and your team can use HERMES to help answer a variety questions such as:

  • What will be the impact of introducing new technologies?
  • What are the effects of altering the characteristics of health products?
  • How does the configuration and the operations of the supply chain (e.g., storage devices, shipping frequency, personnel or ordering policy) affect performance and cost?
  • What may be the effects of differing conditions and circumstances (e.g., power outages, delays, inclement weather, etc.)?
  • How should one invest or allocate resources most effectively resources (e.g., adding refrigerators vs. increasing transport frequency)?
  • How can product delivery be optimized?

Please visit the HERMES’ website for download instructions, the User Guide, Tutorials and more.