Flu and Other Pathogens

Delphi systems developed before the COVID-19 pandemic typically target seasonal Influenza (“Flu”), but can also be used to study other diseases including Chikungunya, Dengue, and Norovirus.

Flu Forecasting

Since 2013, Delphi has supported the U.S. CDC’s Influenza Division in advancing and growing a scientific community around influenza forecasting. That year, we participated in the CDC’s inaugural “Predict the Influenza Season Challenge.” We’ve been perennial leaders in forecasting accuracy ever since, taking part in further flu forecasting challenges. In 2019, we were designated a National Center of Excellence for Influenza Forecasting, which is a CDC-funded and CDC-designated center working on advancing influenza forecasting, and enabling and improving the usefulness of forecasts of both seasonal and pandemic influenza.

Resources and Tools

Epidata for Flu

The Delphi Epidata repository and API, originally released in 2016, collects, processes, stores and provides real-time access to epidemiological surveillance signals, as well as access to historical versions of each signal (“what was known when”). We continuously receive data from multiple sources and extract signals related to flu, dengue, and other pathogens. In early 2020, we started adding many COVID-19 related data sources and signals under an endpoint called COVIDcast, which grew to become the dominant part of the Epidata collection.


EpiVis is an interactive tool for visualizing epidemiological time-series data. Users may explore their own data or utilize existing time series from the numerous data sources provided by the Epidata API.

ILI Nearby

In continuous operation since 2016, ILI Nearby is a real-time flu tracking system which utilizes sensor fusion methodology to bring together multiple signals to nowcast (estimate in real-time) the prevalence of Influenza-Like-Illness ("%ILI") in each U.S. state and broader regions of the US. Note: Since early 2020, %ILI has lost much of its meaning for flu surveillance because of its overlap with COVID-Like-Illness (CLI) and because of drastic changes in healthcare practices and healthcare-seeking behavior. Consequently, ILI Nearby has not been actively maintained since 2019 and should no longer be relied upon for accurate nowcasting of %ILI in the pandemic and post-pandemic era.

Research Articles

Other Pathogens

Delphi has also worked on other pathogens, including Dengue fever, Norovirus, and Chikungunya. More information about our data on those pathogens is available in our Epidata API.

Research Articles