Restaurants, offices, and other locations open for business amid the coronavirus pandemic are increasingly relying on temperature checks to screen people for infection—but federal officials and public health experts say the practice is largely performative.
Temperature checks increasingly popular—but not particularly effective, experts say
According to the New York Time, the growing popularity of this screening method has spurred a "surge in sales of infrared contact-free thermometers and body temperature scanners"—even as scientific evidence suggests that temperature checks are largely ineffective as a prevention measure.
According to public health experts, while temperature checks could detect people who are very ill, those people likely are already refraining from going out—precisely because they don't feel well. From that perspective, although temperature checks may help remind people that the epidemic "is a big deal," they would only pick up the relatively few people who are unaware of their fever, Thomas McGinn, Northwell Health SVP and deputy physician in chief, said.
Moreover, according to McGinn, the absence of a fever "means nothing. It's not a very sensitive test" for Covid-19, the disease caused by the pathogen. McGinn pointed to a study he led, published in JAMA, that found that of nearly 6,000 patients hospitalized with Covid-19 at a Northwell Health hospital, just 30% had a fever when they were admitted.
In addition, evidence indicates that many of the people driving transmission are "silent spreaders," A. David Paltiel, a professor of health policy and management at the Yale School of Public Health, said.
"You are maximally infectious before you exhibit symptoms, if you exhibit any symptoms at all," Paltiel explained. "You can be exposed and incubating the virus, and be beginning to shed massive amounts of transmissible virus and be a superspreader, without actually exhibiting any symptoms like a fever"—and temperature checks won't do anything to stop these "ticking time bombs."
Ultimately, temperature checks are like "getting the oil checked before you go on a long car trip," said David Thomas, an infectious disease specialist at Johns Hopkins University School of Medicine. "It makes you feel better, but it's not going to keep you from wrecking the car or prevent the tires from falling off. It's not going to make your trip any safer."
What experts recommend instead
Instead of relying on temperature checks alone, experts recommend that organizations and institutions deploy a suite of preventive measures and tactics—which can include, but are not limited to, temperature checks, the Times reports.
"Temperature checks are one part of that, but they are only one part," Peter Kuhn, a professor of biological science, medicine, and engineering at the University of Southern California, said, arguing they should be used alongside other safety measures, such as mask requirements and social distancing.
"If anyone would argue that [temperature checks alone] can provide complete safety for indoor dining, that is completely wrong," Kuhn added. "It's not a magic bullet."
CDC echoed that sentiment in July, when it updated its guidance to businesses by acknowledging that checking people's temperature and other symptoms "will not be completely effective," given that asymptomatic people and those with mild symptoms may pass such tests. Even though the agency provided detailed guidance on how to most safely conduct temperature checks, it cautioned that "health checks are not a replacement for other protective measures such as social distancing."
CDC went a step further last week, announcing that it would eliminate its temperature checks and symptom screening for international passengers arriving at U.S. airports, since that approach cannot screen out infected people who "have no symptoms or fever at the time of screening, or only mild symptoms."
Instead, CDC said it will implement a new strategy that "focuses on the continuum of travel and the individual passenger, including pre-departure and post-arrival education, efforts to develop a potential testing framework with international partners, and illness response." The strategy will include health education initiatives before, during, and after flights; voluntary contact information collection; potential testing; and post-arrival recommendations about self-monitoring (Rabin, New York Times, 9/14; Oliver, USA Today, 9/10).