Preface: COVID-19 Scenario Modeling Hubs

In the years preceding the COVID-19 pandemic, there was a growing interest for forecasting and scenario projections related to infectious disease dynamics. This led to the development of multi-model challenges centered around a series of common questions, with an emphasis on linking modeling to policy (Halloran et al., 2008, Prasad et al., 2023, Shea et al., 2020, RAPIDD Ebola Forecasting Challenge group, 2018). No one had foreseen the imminent emergence of COVID-19, which prompted a swift mobilization of diverse modeling efforts to create real-time models aimed at enhancing situational awareness and guiding mitigation strategies. The COVID-19 Scenario Modeling Hub (SMH) was set up in the midst of this, with the aim to coordinate efforts and provide consolidated modeling evidence to guide decision making in the US (Loo et al., 2024). From its inception in December 2020 to the full release of the Epidemics supplement in June 2024, SMH has produced 18 rounds of long-term (ranging from 3 months to 2 year horizons) COVID-19 projections, 4 rounds of influenza projections, and one round of respiratory syncytial virus (RSV) projections. This effort has involved 30 individual participating models and has generated advances in the science of multi-model ensembles (Bay et al., 2024, Wade-Malone et al., 2024) and the establishment and coordination of modeling hubs (and tools to support these hubs) (European Modeling Hubs, 2024, European Respiratory Diseases Forecasting, 2024, The Consortium of Infectious Disease Modeling Hubs, 2024).

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