Are Fever Checks a Good Gatekeeper for Covid? - The New York Times

Coronavirus outbreaks — like one in East Lansing, Mich., this summer that infected 187 people — have been traced to superspreading gatherings at bars and restaurants.

Cuomo has allowed businesses to demand that patrons undergo temperature checks, and to deny admission to those who refuse or have a fever, and he is requiring restaurants in New York City that resume indoor dining to check customers’ temperatures.

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.

— 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.

“We now have a better understanding of Covid-19 transmission that indicates symptom-based screening has limited effectiveness because people with Covid-19 may have no symptoms or fever at the time of screening, or only mild symptoms,” the C.D.C.

Most people who spike a fever feel lousy, and presumably would cancel their dinner plans, said Dr.

Temperature checks might pick up a few individuals who are unaware of their fever, he said.

But here’s the rub: While fever can be a symptom of Covid-19, the disease caused by the coronavirus, not everyone infected with the virus develops a fever, or many other symptoms, for that matter.

A recent study from South Korea published in JAMA Internal Medicine in August offered even more proof, finding that infected individuals who don’t feel ill may carry just as much virus in their nose, throat and lungs as those with symptoms — and for almost as long.

quietly updated its guidance to businesses, acknowledging that symptom and temperature checks “will not be completely effective” because asymptomatic individuals and those with vague symptoms will pass the screenings

The bottom line, officials from the federal health agency said, is that screening employees for Covid-19, including using temperatures checks, before they return to work is “an optional strategy businesses can consider implementing depending on their local situation.”

Peter Kuhn, a professor of biological science, medicine and engineering at the University of Southern California, said his studies suggested that fever is often a first symptom of the coronavirus

And while temperature checks may be useful, he said they should be used in conjunction with a comprehensive package of safety measures that include requiring masks and social distancing, and ensuring good ventilation and access to a flow of fresh air