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Are Temperature Checks Just Covid-Prevention Theater?

(Bloomberg Opinion) -- Suddenly, thermometers are everywhere. Reopening colleges are planning to follow students’ temperatures. The New York Stock Exchange won’t let a member with a fever onto the floor. At my doctor’s office the other day, my temperature was taken both at the entrance and minutes later in the examination room, before I could receive the required injection that had brought me out of shelter.

Measuring the body’s heat has become the latest solution to the how-to-open-in-a-pandemic conundrum. I understand, and even share, the determination to get things moving again. But I worry that our new enthusiasm for constant temperature-taking might turn out to be mainly security theater, an effort to make us feel better without regard to whether we're actually safer. The reasons for my uneasiness are several.

For one thing, we’re not sure what fever to look for. In the words of Consumer Reports, “scientists have not identified a specific fever pattern tied to this disease.” Most of those who have both Covid-19 and a fever will be displaying other symptoms too; in other words, they’ll be easy to spot. But the significant number of infected people who are asymptomatic — perhaps 35% of all coronavirus patients, according to the CDC — likely won’t have a fever at all. So temperature screening will miss a lot of carriers.

Moreover, studies of the relationship between fever and Covid-19 are all over the map. According to a literature review released in April by the Center for Evidence-Based Medicine, fever is present in between 82 and 87 percent of mild or moderate cases of Covid-19. On the other hand, one study of Covid-19 patients sick enough to be admitted to hospitals found that only 30 percent presented with fever. Other studies have found much higher figures, but that's the point: We don't know.

Bear in mind that fevers have countless causes, many not even related to infectious disease. Only a minority of those blocked from boarding planes or entering stores will have high temperatures resulting from the body’s battle against this particular illness.

Even strenuous exercise can raise body temperature. This isn’t news. A guide for nurses published in the 19th century carried the same warning. I mention this particular example because when I arrive early for an appointment, it’s long been my habit to take a brisk walk rather than sit in a waiting room. Now I have to worry that my desire to squeeze in a little exercise whenever I can might keep me out of places I need to be.

Here’s another problem: We don’t agree on what a fever is. Oh, there are formal definitions. Both CDC and WHO say that a person has a fever when temperature rises above 100.4 degrees Farenheit. But there’s long been disagreement within the medical profession over whether that’s the right number. The CDC-WHO definition stems from research by the pioneering German physician Carl August Wunderlich ... published in 1868. It’s Wunderlich, too, whose 19th-century data was used to establish 98.6 as normal body temperature.(1) We now know, however, that normal body temperature is closer to 97.5 degrees — and in many people, even lower. If the newer number is correct, then a patient with a temperature of, say, 99.3 — well within the “old” normal range — might well be febrile. Should we keep that person out of the shopping mall?

On top of all that, our thermometers might be wrong. A 2014 literature review by the Canadian Agency for Drugs and Technologies in Health found accuracy issues with many devices used to measure body temperature non-invasively. Thermometers that measure temperature in the ear tend to be more accurate than those that measure from a distance. This is a concern that matters, given the rush by employers to install thermal cameras and similar devices.

All of which leads us to another big question: the potential for invasions of privacy. The American Civil Liberties Union argues in a recent white paper that we shouldn’t do routine temperature checks until we know more about both the accuracy of the devices used and the relationship of temperature to Covid-19. Among the organization’s particular concerns is that the rise of automated temperature monitors that scan people from a distance. Their use, the ACLU warns, might transform the workplace into a realm of constant health surveillance of employees.

The caution is sensible, but I wonder whether it misses the point. I doubt that many experts would seriously argue that constant temperature monitoring will do much to curb the spread of Covid-19 or other diseases. I suspect that the true, if unspoken, purpose of using thermometers before allowing employees into the office or patrons into the opera house is to reassure a frightened public. If public confidence grows, we might yet find it possible to return to some semblance of normality.

My point isn’t that the ubiquity of the thermometers is all smoke and mirrors. But by now, those with businesses or governments to run have to be wondering whether the balance between prudence and freedom might have swung too far in one direction. If taking temperatures is helpful in getting things up and running, they’re willing to try.

On the other hand, if we really want to go down this road, screening people for Covid-19 before allowing them to mingle with other people, maybe temperature is the wrong thing to measure. The aforementioned literature review from the Center for Evidence-Based Medicine suggests that sudden onset of ansomnia — loss of the sense of smell — might be a stronger indicator that a person has the disease.(2)

So maybe what we really need is have everybody sniff a scented candle before they can go back to work.

(1) Wunderlich himself, by the way, turns out to have misanalyzed his own data.

(2) Ansomnia related to Covid-19 may also predict that the disease is likely to be moderate rather than severe.

This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.

Stephen L. Carter is a Bloomberg Opinion columnist. He is a professor of law at Yale University and was a clerk to U.S. Supreme Court Justice Thurgood Marshall. His novels include “The Emperor of Ocean Park,” and his latest nonfiction book is “Invisible: The Forgotten Story of the Black Woman Lawyer Who Took Down America's Most Powerful Mobster.”

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