From Burger King to the Bellagio, businesses are touting the fact that their employees receive regular temperature checks.

But with summer heat already hammering down, how reliable are they?

Infrared forehead thermometers provide a fast, easy, contact-free way to screen large numbers of people. But they must be used correctly, which means holding them at a specified distance — typically an inch or two from the forehead.

Medical studies and user guides warn heat and exercise can affect body temperature, as can age, gender, medications and time of day.

Different thermometer types also have different fever thresholds.

The relative accuracy of the devices is not well studied and remains unclear.

What is clear is that measuring fever is not the same as detecting, or ruling out, a virus.

→ Read The Latest News On The Coronavirus Disease