Caveats of Syndromic Surveillance for Covid-19

This article is part of the Syndromic Surveillance and Covid-19 collection on Thoughtfaucet.

There are caveats to all data projects. I do not believe any of these undermine the work and thinking. But they are important to note (and I hope you mention other caveats as well–it improves the project) and discuss if necessary. But all the same, remember that John Snow removed the pump handle for a reason.

Syndromic Surveillance Factors

  • Syndromic surveillance from tools such as EpiQuery are tracking what people say upon arrival to the emergency department. They specifically do not show diagnosis or what happens after they arrive. Neither Influenza-like Illness nor Respiratory cases are necessarily Covid-19 cases.

Human factors

  • I entered this data by hand into a spreadsheet. I could have made an error. I double check everything but still I am human.
  • The data itself has the caveats of data entry and maintenance. While working on this project I noticed that the download CSV version differs from the web interface data. Not by a giant amount, but it’s definitely not the same. This project uses the web interface version which I can confirm is updated after it is initially entered.
  • The data is encoded by humans in the emergency departments.

Disease Factors

  • Some of the aspects of Covid-19 present in ways which may result in their encoding going into various parts of EpiQuery that are not being observed by my methods.
  • The things we know about coronavirus are still emerging. Some of the key data for these graphs may change, such as the doubling rate. How the disease progresses appears to be very dependent on the human behavior in relation to it and how well medical systems cope with the surge in demand.

Society Factors

  • Increases after March 1 and March 10 could be people getting inspired by announcements, of first case and first local death respectively, to check into the ER. This is a critically important caveat for this and all syndromic surveillance methods.
  • Communication about what to do, when to do it, whether to do anything at all has been mixed and sometimes conflicting at the federal, state, and local level. These communication issues likely have an influence on whether people show up at the emergency department or not.
  • Maybe it’s all just some artifact of an aging population.

Unknown Factors

  • The increase we see may not be Covid-19. Maybe it’s a fluke. Maybe it’s some other influenza-like thing which has different characteristics.

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