Fever checks: Doubts about whether they are effective gatekeepers

In recent weeks, a new cadre of gatekeepers armed with thermometer guns has appeared at the entrances of hospitals, office buildings and manufacturing plants to screen out feverish individuals who may carry the coronavirus.

Employees at some companies must report their temperature on apps to get clearance to come in. And when indoor dining resumes at restaurants in New York City later this month, temperature checks will be done at the door.

Since the beginning of the pandemic, the practice of checking for fever has become more and more commonplace, causing a surge in sales of infrared contact-free thermometers and body temperature scanners even as the scientific evidence indicating they are of little value has solidified.

Gov. Andrew M. Cuomo of New York last week called for checking patrons’ temperatures as one of several ground rules for resuming indoor dining in restaurants, along with strict limits on the number of tables and a mask mandate for diners when they are not seated. Restaurants also will be required to obtain contact information from one guest at each table. ...

But while health officials have endorsed masks and social distancing as effective measures for curbing the spread of the coronavirus, some experts scoff at fever checks. Taking temperatures at entry points is nothing more than theater, they say, a gesture that is unlikely to screen out many infected individuals, and one that offers little more than the illusion of safety. ...

... The C.D.C. defines a fever as a temperature of 100.4 degrees Fahrenheit or higher; some reports have questioned the accuracy of thermometer guns, however.

While temperature checks may identify people who are seriously ill, those are the people who probably won’t be socializing much or going out for meals. And a growing body of evidence suggests that many of those who are driving transmission are so-called silent carriers — people who have been infected but feel fine, and don’t have a fever or any other symptoms.

Earlier this week, the C.D.C. — which in May told employers to consider checking workers daily for symptoms like fever, but appeared to reverse itself in July — said it would stop requiring airport health screenings beginning Sept. 14 for international passengers from China, Iran, Brazil and other countries because the checks can’t identify silent carriers.  ...