FDA Defines Correct Operation of "Fever Cameras"

Published May 26, 2020 11:48 AM
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The US FDA has now defined the correct operation of "Thermal Imaging Systems", colloquially known as "fever cameras".

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Many in video surveillance have interpreted the FDA's decision to temporarily lift 510(k) clearance requirements for fever cameras to mean that 'anything goes', ignoring well-established global standards.

However, this latest FDA guidance show that even amid a fever camera Gold Rush, the agency believes such systems need to be set up and operated "correctly".

In this we post, we examine this new FDA document, including:

  • Background: FDA Studies Show Fever Cam Operation Importance
  • FDA Statement to IPVM
  • Fever Cameras "Only Effective" Under These Conditions
  • "Careful" Setup Needed
  • What Is A Right Environment?
  • Secondary Confirmation A Must
  • Remove Hats, Glasses, Hair Obstructions/ Wait 15 Minutes
  • Process People One At A Time, No "Mass Fever Screening"
  • Locations Recommended: Airports, Offices, Supermarkets, Concerts, Hospital ERs
  • No Distance Recommendation, But Clearly Close
  • Blackbody Only Required If Manufacturer Recommends

Fever Cameras "Work Effectively Only" Under These Conditions

In its new recommendations (issued May 13) the FDA says fever cameras only work effectively when all 4 elements below are true:

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The most fundamental issue is that vendors are overwhelmingly marketing passive screening of anyone walking by wearing whatever while the FDA, consistent with global standards, is making clear that people must follow instructions.

Remove Hats, Glasses, Hair Obstructions/ Wait 15 Minutes

In particular, the FDA says a person's "whole face" should be measured without face obstructions (e.g., masks, glasses, hats, scarves, hair):

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The FDA even recommends people wait "at least 15 minutes" in the "measurement room" to make sure their face skin temperature is not affected by outdoor weather.

In real life, the 15 minutes recommendation is certain to be difficult to implement, with people likely unwilling to wait around in a room to be processed. However, the opposite is frequently happening with people being screened outdoors or immediately upon walking into a facility with the fever camera commonly pointed at the front door.

Process People One At A Time, No "Mass Fever Screening"

The FDA explicitly says "only one person" should be measured at a time:

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The agency states that fever cams which read several people at once "have not been shown to be accurate":

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Finally, the FDA recommends against "mass fever screening" of people":

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As IPVM has noted before, this goes counter to some manufacturers, such as Sunell which showcased its Panda Cam measuring over 40 people at once:

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Update: IPVM asked the FDA on what evidence (e.g. tests or data) they based their determination that screening multiple people is not accurate. They told us that there was no scientific literature that indicates success for mass screening with a fever camera, and that there were technical issues (like not having enough pixels, bad angles) when measuring multiple people.

Proper Setup Example

The FDA supplies this illustration showing a good fever cam setup:

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It's worth noting that the fever cam (Infrared Thermograph or "IRT") should be positioned parallel to the target's face, not higher up/angled as some manufacturers have shown, e.g. this Dahua video:

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What Is A Right Environment?

A good environment must have stable room temperature, low humidity, and avoid harsh lighting, air conditioning drafts, and direct sunlight:

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Locations Recommended: Airports, Offices, Supermarkets, Concerts, Hospital ERs

The FDA says fever cams may not be a good option for nursing homes as a single missed fever could spread disease, so a more accurate/thorough solution should be implemented.

However, for "airports, workplaces, grocery stores, concert venues" and "other areas where you are trying to screen large groups", fever cameras "could be considered" as "part of a larger approach to risk management."

The FDA also recommends fever cams for hospital emergency rooms in order to "quickly assess temperature and triage patients":

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Secondary Confirmation A Must

Fever cams cannot be solely relied upon to determine if someone has a fever, requiring confirmation "by another method":

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While this policy does not elaborate what secondary method should be used to confirm a fever, in previous guidance, the FDA recommended thermometers, specifically "non-contact infrared thermometer (NCIT) or clinical grade contact thermometer".

Blackbody Only Required If Manufacturer Recommends

The FDA states that "some devices do not require" a blackbody and they should only be used if the manufacturer recommends it. If so, it should be turned on 30 minutes prior to heat up:

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Indeed, not all fever cam solutions require blackbodies. Hikvision salespeople have recommended not using blackbodies (unlike Dahua) and FLIR does not recommend them with their specific EST lines. However, in our testing of Hikvision without a blackbody we found significantly increased accuracy problems and do not recommend such an approach. Our testing of FLIR is ongoing currently and we plan to release that report in early June.

No Distance Recommendation, But Clearly Close

The FDA doesn't give a specific distance recommendation, however, its examples all show people positioned close to the camera:

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The FDA says "follow the manufacturers instructions" when it comes to a specific distance.

Background: FDA Studies Show the Importance of Proper Operation

FDA scientists have published two studies on fever cam operation (one last year and another just this month) showing the importance of correct implementation, e.g. all face obstructions were removed while subjects were screened one-at-a-time and even made to wait 15 minutes prior to being processed.

The most recent study found, conclusively, that sticking to International Fever Cam Standards (which are detailed and strict) increases fever cam accuracy:

adherence to international consensus guidelines regarding IRT [infrared thermograph] system specifications and implementation contributes to optimization of measurement accuracy and detection of febrile individuals

FDA Statement to IPVM

IPVM asked the FDA why it issued this document and how it contrasts with its decision to temporarily relax the 510(k) clearance requirement last month.

The FDA told us that this guidance help "explain how to correctly use these devices" and that it may review anyone "marketing thermography devices in ways that pose risks to public health". Below is their full statement:

The FDA recognizes the increased interest in telethermographic systems during the COVID-19 pandemic. We provided an update to our website to help users and the public understand the benefits and limitations of these devices, and their role during the public health emergency. The update helps explain how to correctly use these devices to accurately measure someone’s temperature and clarifies questions around different environments in which these devices could be used. This information should be used in conjunction with the guidance issued in April.

This guidance does not change existing regulations or requirements; instead, it announces that the FDA does not intend to object, under the circumstances described in the guidance and where such use does not create undue risk, to the distribution and use of certain devices without compliance with certain regulations and requirements, in order to help protect public health during this emergency.

As the agency always does, if the FDA receives information that a manufacturer is marketing a medical device in violation of regulations, the FDA prioritizes review of such action based on risk to public health and available resources. If the FDA receives information that indicates manufacturers are marketing thermography devices in ways that pose risks to public health, the same principles would apply to the review of that information.


Now that the FDA has publicly announced correct operation steps, US sellers have little excuse to ignore them, and may risk legal action if the FDA determines their setups "pose risks to public health".

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