SAN FRANCISCO (KGO) -- At least two major retailers, Amazon and Walmart, have started doing employee temperature checks to prevent the spread of the coronavirus.
Gov. Gavin Newsom this week suggested restaurants may do it when they re-open to diners. But temperature checks aren't perfect.
Fever is one of the symptoms of COVID-19.
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As much as temperature checks might be a tool to screen out infected people, experts say there are just too many variables to be reliable as the sole test.
98.6 degrees as the normal body temperature dates back to research by a German doctor in 1851.
However, there's evidence it's about one degree lower today. That's a factor that can't be overlooked with proposals to do temperature checks for employees and customers, says our special correspondent, Dr. Alok Patel.
"Your temperature, my temperature, might vary depending on medications we've taken, clothing, time of day," he noted. "We know temperature can vary based on their age, their demographics, even gender."
Even the type of thermometer used will produce different results.
Rectal thermometers are widely considered the most accurate but not practical for public screenings.
Dr. Patel says touchless infrared devices measure skin temperature, not body temperature. Skin temperature can be influenced by cosmetics or even room temperature.
100.6 is the benchmark used to indicate a fever. However, Dr. Patel says an infected person could slip by.
"If you have back pain and you take ibuprofen or Tylenol, and you happen to have coronavirus, you very well could be dropping your fever, and you could walk right past one of those temperature screens," he said.
There are other factors a temperature check could miss.
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Studies so far indicate typical COVID-19 patients don't develop fever until day five, but it can range from day two to 14. A study in China suggests people are most infectious two to three days before getting a fever.
The Equal Employment Opportunity Commission has issued guidance that temperature checks are allowed during the pandemic.
However, a person denied access could argue a case of discrimination, according to employment law specialist Michael Warren at the McManis Faulkner law firm in San Jose.
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"So it's important if a temperature screen process should be done in an unbiased, nondiscriminatory, neutral manner," he said.
Dr. Patel and other medical experts say temperature checks are just one tool for screening. Testing and questionnaires are important, too, along with social distancing and hand washing.
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