To cite the covidcast package in publications use:

Arnold T, Bien J, Brooks L, Colquhoun S, Farrow D, Grabman J, Maynard-Zhang P, Reinhart A, Tibshirani R (2025). covidcast: Client for Delphi's COVIDcast Epidata API. R package version 0.5.3, https://cmu-delphi.github.io/covidcast/covidcastR/.

To cite COVIDcast data in publications use:

Reinhart A, Brooks L, Jahja M, Rumack A, Tang J, Agrawal S, Saeed WA, Arnold T, Basu A, Bien J, Cabrera ÁA, Chin A, Chua EJ, Clark B, Colquhoun S, DeFries N, Farrow DC, Forlizzi J, Grabman J, Gratzl S, Green A, Haff G, Han R, Harwood K, Hu AJ, Hyde R, Hyun S, Joshi A, Kim J, Kuznetsov A, La Motte-Kerr W, Lee YJ, Lee K, Lipton ZC, Liu MX, Mackey L, Mazaitis K, McDonald DJ, McGuinness P, Narasimhan B, O’Brien MP, Oliveira NL, Patil P, Perer A, Politsch CA, Rajanala S, Rucker D, Scott C, Shah NH, Shankar V, Sharpnack J, Shemetov D, Simon N, Smith BY, Srivastava V, Tan S, Tibshirani R, Tuzhilina E, Van Nortwick AK, Ventura V, Wasserman L, Weaver B, Weiss JC, Whitman S, Williams K, Rosenfeld R, Tibshirani RJ (2021). “An open repository of real-time COVID-19 indicators.” Proceedings of the National Academy of Sciences, 118(51). doi:10.1073/pnas.2111452118.

For more information about citing the datasets provided by the API, including their licensing, see: https://cmu-delphi.github.io/delphi-epidata/api/covidcast_licensing.html

Corresponding BibTeX entries:

  @Manual{covidcast,
    title = {{covidcast}: Client for {D}elphi's {COVID}cast {E}pidata
      {API}},
    author = {Taylor Arnold and Jacob Bien and Logan Brooks and Sarah
      Colquhoun and David Farrow and Jed Grabman and Pedrito
      Maynard-Zhang and Alex Reinhart and Ryan Tibshirani},
    year = {2025},
    note = {R package version 0.5.3},
    url = {https://cmu-delphi.github.io/covidcast/covidcastR/},
  }

  @Article{covidcastPNAS,
    title = {An open repository of real-time {COVID}-19 indicators},
    author = {Alex Reinhart and Logan Brooks and Maria Jahja and Aaron
      Rumack and Jingjing Tang and Sumit Agrawal and Wael Al Saeed and
      Taylor Arnold and Amartya Basu and Jacob Bien and Ángel A.
      Cabrera and Andrew Chin and Eu Jing Chua and Brian Clark and
      Sarah Colquhoun and Nat DeFries and David C. Farrow and Jodi
      Forlizzi and Jed Grabman and Samuel Gratzl and Alden Green and
      George Haff and Robin Han and Kate Harwood and Addison J. Hu and
      Raphael Hyde and Sangwon Hyun and Ananya Joshi and Jimi Kim and
      Andrew Kuznetsov and Wichada {La Motte-Kerr} and Yeon Jin Lee and
      Kenneth Lee and Zachary C. Lipton and Michael X. Liu and Lester
      Mackey and Kathryn Mazaitis and Daniel J. McDonald and Phillip
      McGuinness and Balasubramanian Narasimhan and Michael P. O’Brien
      and Natalia L. Oliveira and Pratik Patil and Adam Perer and
      Collin A. Politsch and Samyak Rajanala and Dawn Rucker and Chris
      Scott and Nigam H. Shah and Vishnu Shankar and James Sharpnack
      and Dmitry Shemetov and Noah Simon and Benjamin Y. Smith and
      Vishakha Srivastava and Shuyi Tan and Robert Tibshirani and Elena
      Tuzhilina and Ana Karina {Van Nortwick} and Valérie Ventura and
      Larry Wasserman and Benjamin Weaver and Jeremy C. Weiss and
      Spencer Whitman and Kristin Williams and Roni Rosenfeld and Ryan
      J. Tibshirani},
    year = {2021},
    journal = {Proceedings of the National Academy of Sciences},
    volume = {118},
    number = {51},
    doi = {10.1073/pnas.2111452118},
  }