COVID-19 Trends and Impact Survey

Since April 2020, Delphi has conducted a voluntary survey about COVID-19, distributed daily to users in the United States via a partnership with Facebook. This survey asks respondents about COVID-like symptoms, their behavior (such as social distancing), mental health, and economic and health impacts they have experienced as a result of the pandemic. A high-level overview of the survey is posted on the COVIDcast website, and an international version is conducted by the University of Maryland. Data collection ceased on June 25, 2022.

The CTIS Methodology Report describes the survey design, data collection process, weighting, and aggregation processes, and is the primary reference for researchers working with the survey data. This website describes details specific to the US version of the survey and documents the individual response data, which is available to researchers with a signed Data Use Agreement. If you are a researcher and would like to get access to the data, see our page on getting data access.

If you have questions about the survey or getting access to data, contact us at


The survey results dashboard provides a high-level summary of survey results. Geographically aggregated data from this survey is publicly available through the COVIDcast API as the fb-survey data source. Demographic breakdowns of survey data are publicly available as downloadable contingency tables.

CTIS data has been used in numerous peer-reviewed publications.


The US COVID-19 Trends and Impact Survey (CTIS) is a project of the Delphi Group at Carnegie Mellon University. Team members include:

  • Alex Reinhart, Principal Investigator
  • Wichada La Motte-Kerr, Survey Coordinator (2020-2022)
  • Robin Mejia, survey advisor
  • Nat DeFries, statistical developer and data engineer
  • Eu Jing Chua (2020-2021) and Mashrin Srivastava (2021-2022), data analysis interns
  • plus support from many members of the Delphi team

The survey protocol is reviewed by the Carnegie Mellon University Institutional Review Board.

The support of several institutions makes the survey possible. Facebook supports the survey through recruitment (participants are invited via their News Feed), survey sampling and weighting procedures, technical assistance in survey design and implementation, and coordination with researchers and public health officials. The University of Maryland’s Social Data Science Center conducts a global version of the survey, and we coordinate closely on survey design and implementation. Delphi collects, aggregates, and distributes the US survey data, and retains ultimate responsibility for the US survey instrument and data.

We develop the survey collaboratively with data users, public health officials, and others. If you are interested in getting involved, see our collaboration and survey revision information.

Citing the Survey

Researchers who use the US survey data for research are asked to credit and cite the survey in publications based on the data. Specifically, we ask that you:

  1. Include the acknowledgment “This research is based on survey results from Carnegie Mellon University’s Delphi Group.”
  2. Cite our paper describing the survey:

    Joshua A. Salomon, Alex Reinhart, Alyssa Bilinski, Eu Jing Chua, Wichada La Motte-Kerr, Minttu M. Rönn, Marissa Reitsma, Katherine Ann Morris, Sarah LaRocca, Tamar Farag, Frauke Kreuter, Roni Rosenfeld, and Ryan J. Tibshirani (2021). “The US COVID-19 Trends and Impact Survey: Continuous real-time measurement of COVID-19 symptoms, risks, protective behaviors, testing, and vaccination”, Proceedings of the National Academy of Sciences 118 (51) e2111454118.

  3. The data use agreement requires that if you disclose survey microdata, Delphi must agree on the aggregation method that you will use to ensure reported estimates do not disclose any individual identifiable information, including individual survey results. If you are unsure whether a particular aggregation will prevent disclosure of individual survey results, please email us at
  4. Finally, send a copy of your publication, once it appears publicly as a preprint or journal article, to

When referring to the survey in text, we prefer the following formats:

  • Long form (such as in an introduction or methods description): “The Delphi Group at Carnegie Mellon University U.S. COVID-19 Trends and Impact Survey, in partnership with Facebook”.
  • Short form (used after the long form has been introduced): “The U.S. COVID-19 Trends and Impact Survey”
  • Acronym form: “Delphi US CTIS”

Prior to July 2021, the survey was known as the COVID Symptom Survey (CSS), and some older documentation and publications may still refer to this name. We prefer that new publications and materials refer to the new name.

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