The Delphi Blog

News, findings, and musings from the epidemic tracking and forecasting team.

New and Improved COVID Symptom Survey Tracks Testing and Mask-Wearing

Alex Reinhart
Beginning on September 8, 2020, we deployed a new version of our symptom survey. Facebook helps us recruit tens of thousands of respondents daily, and the new survey gives us unprecedented insights into the effects of COVID-19 across the United States. Today we release new public datasets and share maps revealing access to COVID testing, test results, and public use of masks.

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Accessing Open COVID-19 Data via the COVIDcast Epidata API

Kathryn Mazaitis and Alex Reinhart

One of our primary initiatives at the Delphi COVIDcast project has been to curate a diverse set of COVID-related data streams, and to make them freely available through our COVIDcast Epidata API. These include both novel signals that we have collected and analyzed ourselves, such as our symptom survey distributed by Facebook to its users, Google’s symptom survey whose results are delivered to us, the percentage of doctor’s visits due to COVID-like illness, and results from Quidel’s antigen tests; and also existing signals, such as the confirmed case counts and deaths reported by USA Facts and Johns Hopkins University. The COVIDcast API freely provides researchers and decision-makers with the data they need to conduct their work, and is conveniently accessible via easy-to-use Python and R packages.

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Can Symptoms Surveys Improve COVID-19 Forecasts?

Ryan Tibshirani

Building on our previous two posts (on our COVID-19 symptom surveys through Facebook and Google) this post offers a deeper dive into empirical analysis, examining whether the % CLI-in-community indicators from our two surveys can be used to improve the accuracy of short-term forecasts of county-level COVID-19 case rates.

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COVID-19 Symptom Surveys through Google

Ryan Tibshirani

Since April 2020, in addition to our massive daily survey advertised on Facebook, we’ve been running (even-more-massive) surveys through Google to track the spread of COVID-19 in the United States. At its peak, our Google survey was taken by over 1.2 million people in a single day, and over its first month in operation, averaged over 600,000 daily respondents. In mid-May, we paused daily dissemination of this survey in order to focus on our (longer, more complex) survey through Facebook, but we plan to bring back the Google survey this fall. This short post covers some key differences between our Google and Facebook surveys, explains the backstory behind the “CLI-in-community” question as it arose through our collaboration with Google, and shares some of our thinking about next steps for the Google survey.

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COVID-19 Symptom Surveys through Facebook

Alex Reinhart and Ryan Tibshirani

Since April 2020, in collaboration with Facebook, partner universities, and public health officials, we’ve been conducting a massive daily survey to monitor the spread and impact of the COVID-19 pandemic in the United States. Our survey, advertised by Facebook, is taken by about 74,000 people each day. Respondents provide information about COVID-related symptoms, contacts, risk factors, and demographics, allowing us to examine county-level trends across the US. We believe that this combination of detail and scale has never before been available in a public health emergency. In this post, we’ll share some of our initial survey findings, show you how to access the data, and highlight some of the exciting new directions that we’re pursuing.

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Hello World!

Roni Rosenfeld and Ryan Tibshirani

Hello from the Delphi research group at Carnegie Mellon University! We’re a group of faculty, students, and staff, based primarily out of CMU together with strong collaborators from other universities and industry. Our group was founded in 2012 to advance the theory and practice of epidemic forecasting. Since March 2020, we have refocused efforts towards helping combat the COVID-19 pandemic, by supporting informed decision-making at federal, state, and local levels of government and in the healthcare sector. Until now, we’ve been pretty “heads down” with our work, and slow to communicate what we’ve been up to. But at last … Delphi finally has a blog! This first post serves as an introduction of sorts. Future posts will dive deeper into our various projects.

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