Fever Scanners for COVID-19 May Be Inaccurate, FDA Warns

Marcia Frellick

March 05, 2021

Editor's note: Find the latest COVID-19 news and guidance in Medscape's  Coronavirus Resource Center.

The US Food and Drug Administration (FDA) has issued an alert to consumers, healthcare providers, and other users of thermal imaging systems that measure body temperature that improper use may produce inaccurate readings.

The systems have been used to check for fevers in schools, workplaces, airports, groceries, and other public buildings, and are offered as a first line of defense in opening up safely during the pandemic. However, it may miss that key indicator of coronavirus infection, according to new research by the surveillance research organization IPVM. The research is set for publication in the Journal of Biomedical Optics, according to the Washington Post.

The FDA alert came Thursday night after the Post shared the research findings with the agency, the Post reports.

The systems are known as telethermographic systems, infrared thermographs, thermal cameras, and "fever cameras." This alert does not pertain to the handheld, noncontact infrared thermometers (NCIT) used to screen individuals, according to the FDA press office.

The FDA says the risks are more likely to be present where thermal imaging systems scan multiple individuals simultaneously.

The FDA has also issued warning letters to firms selling unapproved, uncleared, and unauthorized thermal imaging systems, including Certify Global Inc, Kogniz Inc, Opgal Optronic Industries Ltd, and Thermavis.

Many thermal imaging devices use software that can make a person with a fever appear well, the researchers found.

The Post reports that seven popular scanners "attempt to compensate for the imprecisions of lower-cost sensors and the unpredictable factors of real-world tests by 'normalizing' the readings of people's temperatures.

"But that 'compensating algorithm,' [researchers] argue, severely undermines the devices' medical usefulness. A feverish person with a core temperature of 100.4 degrees, their research found, could be assessed by the test devices as having a temperature of 98 degrees, well within the healthy range."

Still Useful When "Used Properly"

William Maisel, MD, MPH, chief medical officer and director of the Office of Product Evaluation and Quality in FDA's Center for Devices and Radiological Health, stated in the alert announcement, "While thermal imaging is not an effective diagnostic device for COVID-19, it can determine if someone has an elevated temperature, which can be an important risk management tool during the pandemic when used properly. But improper use and marketing of thermal imaging systems may lead to inaccurate temperature readings and pose a potential danger to public health."

To help reduce risk, the FDA is providing recommendations to consumers, healthcare providers, and other users about the proper and improper use of these systems.  

In those recommendations, the FDA advice includes measuring only one person's temperature at a time; and allowing time for a person's skin temperature to adjust to environmental changes, for example when entering a building. Additionally, the recommendations read, the person whose temperature is being scanned should not wear a hat or glasses, and hair should be pulled away from the face.

The FDA typically requires thermal scanners and other medical devices be tested for safety and effectiveness under a 510(k) clearance. But in April, the Post points out, "the agency said it would no longer require premarket reviews or object to unvetted devices that did not 'create an undue risk.' "

The researchers calculate that there are now 200 companies making or advertising the devices. They say the untested systems could fuel a false sense of security that endangers public health.

Additionally, fever is only one possible symptom of a COVID-19 infection and not everyone infected will have an elevated temperature.

Marcia Frellick is a freelance journalist based in Chicago. She has previously written for the Chicago Tribune, Science News and Nurse.com and was an editor at the Chicago Sun-Times, the Cincinnati Enquirer, and the St. Cloud (Minnesota) Times. Follow her on Twitter at @mfrellick .

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