Dr. James Leo is chief medical officer of MemorialCare in Fountain Valley, California.

Leo told Healthline that oral digital thermometers are the most accurate, although they aren’t practical for screening large numbers of people.

Ear thermometers are next, but they can be prone to error, especially if the ear canal is blocked by wax.

According to Leo, noncontact forehead infrared thermometers have poorer accuracy, while infrared thermal cameras used for mass screening show variable accuracy.

“They have not been well-correlated with oral temperatures,” he said.

Dr.Tista Ghosh, an epidemiologist and medical director at Grand Rounds, told Healthline that noncontact, self-administered screenings provide the lowest risk.

“They minimize all person-to-person contact. Some employers may choose to have employees prescreen their own temperatures prior to coming to work, while others may choose worksite screenings,” Ghosh said.

She explained that an infrared thermometer at a self-service station can be accurate, depending on the manufacturer.

“It does not require anyone to administer, and the temperature data may be sent directly to a manager. These models are typically more expensive than a handheld thermometer or thermal scanner,” she said.

Another option is giving employees a handheld infrared thermometer so they can take their own temperature.

“This could, however, be prone to some user error and would require the entry attendants to wear masks, gloves, and other personal protective equipment (PPE),” Ghosh said.

She recommends that businesses check the FDA’s searchable databaseTrusted Source and review any clinical literature available on the accuracy of a particular type of thermometer prior to purchasing.

Does it help stop spread of COVID-19?

Temperature checking will uncover fever in some people.

If those people self-isolate and consult with a doctor, it can help prevent transmission of the coronavirus.

Temperature checking won’t catch all COVID-related fevers, however.

It also can’t identify people who have the coronavirus but no fever.

“Given the fact that a significant number of people with COVID-19 do not develop a fever, the available mass temperature screening technologies may miss the presence of one. In addition, the frequent use of fever-lowering medications such as acetaminophen (e.g., Tylenol) and ibuprofen (e.g., Advil) may also disguise a potential COVID-related fever,” Leo said.

Mass temperature checks may also create a false sense of security.

Taken on its own, experts say absence of fever isn’t a reliable screening tool for COVID-19.

“In fact, we now know that many people with COVID-19 don’t develop significant symptoms at all, or do so in a delayed manner, during which time they are nonetheless able to pass on the infection to others,” said Leo.

He explained that 100°F (37.8°C) is generally used as the cutoff for a true fever with regard to COVID-19 screening.

“There’s nothing magic about this number, and since temperature does fluctuate through the day, with lowest around 4:00 a.m. and highest around 4:00 p.m., true fever may go undetected earlier in the day,” he said.

He said normal daily temperature fluctuation is less than one degree but shouldn’t reach 100°F (37.8°C).

Ghosh noted that screening administered by a supervisor or other staff member can actually create opportunity for person-to-person transmission.

“Therefore, PPE should be made available to the person conducting the screenings and employees being screened should wear face coverings as well,” she said.

Broader strategy needed

For businesses, experts say checking for fever should be just one part of an overall strategy to prevent transmission of COVID-19.

Another crucial step is to limit personal interaction.

“It’s important that people maintain physical distance of at least 6 feet apart as much as possible,” Ghosh said.

“To help people do this, employers should use visible signs or markers to indicate how far 6 feet is. Requiring people to use face masks and frequent handwashing is another way to reduce spread. This could be through regular handwashing breaks, depending on the industry,” she explained.

Surfaces should be disinfected often.

Ghosh pointed out that for temperature screenings to be effective, paid COVID-related sick leave should be implemented.

“People who lack paid sick leave may be incentivized to take fever-masking medication and report to work while ill,” she said.
 

What individuals can do

Individuals have a role to play in reducing transmission of the coronavirus, too.

You can monitor your temperature on your own and alert your doctor if you have a fever.

Coughing, sneezing, or simply talking near others can increase risk.

“We are learning that a substantial percentage of people actively infected with and able to spread COVID-19 have no symptoms at all, which makes universal source control critical for avoiding further spread of COVID-19,” Leo said.

“Universal source control means, first and foremost, everyone wearing a mask or face covering when out in public. It also means continued careful attention to strict handwashing, avoiding touching your face or head without first washing your hands, and whenever possible, maintaining at least 6 feet social distance,” he said.

If during a mass screening you’re found to have a fever, Leo suggests confirming it with a digital oral thermometer.

While a fever doesn’t mean you have COVID-19, it’s a possibility.

For that reason, isolate yourself from others and consult with your doctor.

“If you do have COVID-19, it’s important not to come out of isolation too soon,” Ghosh said.

Continue to stay home if you have symptoms such as shortness of breath, fever, cough, or loss of taste or smell. Frequent handwashing and sanitizing surfaces will also help reduce transmission of the coronavirus.

“Close contacts need to be identified and quarantined based on the latest CDC guidelinesTrusted Source to prevent widespread illness in the workplace,” Ghosh said. “People should make local health officials aware of positive tests.”