The FDA issued an advisory about the use of thermal imaging systems as screening instruments for the COVID-19 pandemic landing the same day as a warning letter to Certify Global Inc. The agency’s concern is that these systems are being used without consideration for the limitations, including that they are not appropriate for mass screenings due to inaccurate findings that could elevate the risk of spread of the SARS-CoV-2 virus.

The FDA advisory noted the use of such systems as initial temperature assessment and triage of individuals in public areas, including airports, schools and workplaces, relies on appropriate set-up and operation. Proper use requires that individuals who are scanned be given time to adjust to environmental changes, such as changes in ambient temperature, when entering a building. Thermal imaging systems should be used only when ambient temperatures fall between 68° and 76° F and should not be used in areas that are subject to strong light sources, including sunlight. Any conspicuous measurements should be confirmed with a digital thermometer, while the hazard of failing to observe appropriate conditions of use includes an incorrect reading.

The FDA notice does not specifically call out the March 4 warning letter to of Gaithersburg, Md.-based Certify Global, which states that the company’s website offers two thermal imaging systems for telethermographic imaging systems. Among the violative claims are that the two units in question, the Snap XT Pro HID and the Infinity X Pro, can scan up to four individuals in one pass, and can provide seven simultaneous reads, respectively. A search of the company’s website indicated that the products are no longer listed. The warning letter states that Certify lacked a standard regulatory premarket authorization for either of the systems, such as a PMA or a 510(k).

Despite the warning letter’s reference to a standard premarket review, the agency posted an enforcement policy for telethermographic systems in April 2020, which allows for distribution of such systems without approval or clearance for purposes of screening for the SARS-CoV-2 virus. This comes with several stipulations, including that a system demonstrate conformance with one of the 2017 editions of IEC 80601-2-59, although the manufacturer can conduct testing in lieu of conformance with the IEC standard.

This would include demonstration that measurement variability is no greater than 0.9° F, and that thermal stability/drift does not exceed 0.36° F over an interval of time specified by the manufacturer. The policy also requires any elevated body temperatures be checked with a secondary evaluation method, and that a system be used on only one subject at a time.

The FDA advisory recommends that anyone being assessed by such a system remove hats or glasses they may be wearing, adding that hair should be pulled away from the face. However, the agency said the benefits of wearing a mask during the process outweigh any risks of an inaccurate thermographic reading. Whether that policy will change if the Centers for Disease Control and Prevention relaxes its masking recommendations is not clear.

The market for these cameras is still vigorous despite that a year has passed since the onset of the pandemic. Verizon, of Basking Ridge, N.J., said in a Feb. 29 statement that it is working with Zyter Inc., of Rockville, Md., to deploy non-contact temperature assessment at public venues, including sports venues, that can assess six individuals at a time at a distance of up to 20 feet. There are those with misgivings about the reliable performance of these systems, including the American Civil Liberties Union, which cited privacy considerations as a problem along with concerns about whether these systems perform as advertised.

Certify Global did not respond to a request for comment.