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During infectious disease outbreaks, public health experts rely on epidemiological parameter estimates to understand the spread and severity of the outbreak and guide effective public health interventions. These parameters are quantitative estimates that describe key aspects of disease transmission and progression, such as incubation period, reproduction number, and duration of infectiousness.

Modelers and other public health professionals have faced the long-standing challenge of finding reliable epidemiological parameter estimates for a specific pathogen and context, often under intense time pressure.

To address this global challenge, Collaboratory, a flagship initiative of the WHO Hub for Pandemic and Epidemic Intelligence, created a dedicated online community, where experts from across the world could work together on finding solutions.      

Over the last 4 years, the Epidemiological Parameters Community of Practice (CoP) has grown to more than 124 members globally. Building momentum, a Core Technical Working Group was formed to develop a digital public good that makes epidemiological parameter estimates more accessible, transparent and usable for all.

Today, this work reaches a major milestone with the launch of the first Global Repository of Epidemiological Parameters, known as grEPI, now available as a proof of concept. 

A digital public good born from collective expertise

Rather than emerging from a single institution or tool, grEPI is the product of global collaboration enabled by Collaboratory.

grEPI is a publicly accessible repository of epidemiological parameter estimates that streamlines how public health experts access and apply reliable parameters, to produce analytical outputs for public health decision-making. The current proof of concept - an initial version designed to demonstrate its capability and grow through continuous input - includes epidemiological parameter estimates for Ebola, Lassa fever, Marburg, Measles, Mpox, Severe acute respiratory syndrome (SARS) and Zika.

Developing a digital public good of this scale required consensus-building, continuous dialogue and data sourced from multiple independent, but complimentary initiatives.

Collaboratory made it possible to navigate complex questions of scope, governance, and minimum viable functionality, balancing the urgency of delivering a usable resource with the need for scientific rigor and long-term sustainability.

This launch demonstrates what becomes possible when diverse institutions pool expertise, data, and technical capacity, in ways that no single organization could achieve alone. Key contributions included:

• Imperial College London, whose Pathogen Epidemiology Review Group provided the foundation through a human-curated dataset for nine priority pathogens
• London School of Hygiene & Tropical Medicine, which supported analysis through Epiverse-TRACE 
• Public Health Agency of Canada, which advanced AI-driven parameter extraction and contributed a human-curated dataset for viruses with pandemic potential
• WHO Hub for Pandemic and Epidemic Intelligence, which led the overall coordination, administration and technical development of the tool

• Feedback from experts across many partners worldwide, which helped shape the tool’s scope, structure, and scientific direction 

What’s next

With grEPI now live, the focus shifts to testing and improvement. The next phase will concentrate on refining the tool through user feedback, continued migration of epidemiological parameter estimates, establishing shared standards, strengthening governance mechanisms, and building a sustainable community of contributors and users.

The platform is now open for exploration. If you’re interested in contributing to the ongoing development of grEPI, or engaging in discussions around its future, you can leverage the network and collaboration opportunities offered through Collaboratory. Learn more and  get in touch with the Epidemiological Parameters Community of Practice.

Acknowledgements

grEPI Core Technical Working Group: Lisa Waddell, Adam Kucharski, Joshua Lambert, Carmen Tamayo-Cuartero, Anne Cori, Ruth McCabe, Christian Morgenstern, Tricia Corrin, Kusala Pussegoda, WHO Collaboratory Secretariat