Are Coronavirus Temperature Checks Really Effective? Here's What Experts Say

Having a thermometer aimed at your forehead every time you go to a public place is supposed to help slow the spread of COVID-19 by identifying if you're sick—but there are limitations to know about.

Some states are relaxing lockdown orders to allow people to go back to work and visit public places—but life is still far from normal. Among the measures in place to try to ensure COVID-19 doesn’t spread is temperature monitoring, or temperature checks: using infrared thermometers or thermal cameras to identify if a person has a fever and therefore might be infected with coronavirus, and then turning the person away and urging they seek medical care.

Amazon has been doing temperature checks for weeks. Dave Clark, senior vice president of worldwide operations, announced on the company blog on April 2 that Amazon was temperature-checking more than 100,000 employees per day. Anyone registering a temperature over 100.4 degrees Fahrenheit is asked to go home and only come back to work after they’ve been free from fever for three days.

New Jersey-based retail cooperative Wakefern Food Corp. followed suit, reported Supermarket News. In mid-April, the company began using non-contact forehead infrared thermometers to temperature check store associates on their arrival at work and sending home anyone with an elevated temperature.

New York City Mayor Bill de Blasio said on MSNBC’s Morning Joe on April 20 that city workplaces may have to carry out temperature checks when people return to work—provided the city could get its hands on enough thermometers. And in California, Gov. Gavin Newsom said his eventual reopening strategy could include temperature checks at restaurants, per Politico. Other states that are starting to ease their way out of lockdown, such as Alaska, Georgia, Colorado, and Tennessee, are implementing similar measures.

But how much difference will temperature checks make when it comes to the spread of COVID-19? The general consensus among medical experts is that it’s an important measure, but only as part of a much wider strategy—and it has some major limitations.

For starters, some people have COVID-19 and don’t display any symptoms, including a fever. According to the Centers for Disease Control and Prevention (CDC), COVID-19 symptoms can develop anywhere between two and 14 days after exposure. That means you could have the virus, but a temperature check wouldn't catch it because you have no fever yet.

Plus, not everyone who gets COVID-19 runs a fever. Although it’s one of the most common symptoms, the disease presents in many different ways. Aside from the asymptomatic cases, one study—published in the Journal of the American Medical Association on April 22—found that out of 5,700 people seriously ill with COVID-19, two-thirds didn’t have a fever.

Infectious disease expert Amesh A. Adalja, MD, senior scholar at the Johns Hopkins Center for Health Security in Maryland, tells Health that while temperature checks may identify some people who have the coronavirus, it’s not an ironclad measure. “People may be taking over-the-counter fever-reducing medications (like Tylenol for headaches) that would alter the temperature reading by suppressing the fever,” he points out. This could mean people “pass” the temperature check even if they have the disease.

“Fever screening can be one part of a wider system, but it’s still unclear how much marginal benefit there is,” Dr. Adalja adds.

Then there’s the logistical and financial burden of carrying out mass testing—of any sort—in workplaces, retail outlets, schools, and the rest of a the community. “Businesses are struggling to get the necessary equipment, such as personal protective equipment (PPE) as it is,” Lisa Kennedy, chief health economist at the pharmaceutical and biotech strategy firm Innopiphany who has a PhD in infectious diseases, tells Health. “No-touch thermometers are in high demand, so it’s hard to get those.”

If oral thermometers are used, sterilization is an issue. And if people are checking their own temperatures, there’s a greater possibility for error—particularly with ear and forehead scanners—than if it’s done by a trained professional.

While regular temperature checks may become part of post-lockdown life for many of us, experts warn that we shouldn't abandon basic preventive habits and discontinue social distancing entirely. Coronavirus has not been eliminated, and even after shelter-in-place orders expire or are eased, people can still contract the virus...despite the possible widespread use of temperature monitoring.

“Prevention of infection with the new coronavirus is a multi-faceted task,” says Dr. Adalja. “Even with entry screening in place, it’s very important to still wash your hands and practice good hand hygiene throughout the day. For those at high risk, it will also be important that they continue to optimally social distance even when venues are open."

The information in this story is accurate as of press time. However, as the situation surrounding COVID-19 continues to evolve, it's possible that some data have changed since publication. While Health is trying to keep our stories as up-to-date as possible, we also encourage readers to stay informed on news and recommendations for their own communities by using the CDC, WHO, and their local public health department as resources.

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