“ As of Feb. 23, 2020, more than 46,000 travelers were screened with NCITs at U.S. airports, and only one person was identified as having SARS-CoV-2," says Wright. "In a second example, CDC staff and U.S. customs officials screened approximately 268,000 travelers through April 21, 2020, finding only 14 people with the virus."
From a November 2020 CDC report, Wright and Mackowiak provide further support for their concern about temperature screenings for COVID-19. The report, they say, states that among approximately 766,000 travelers screened during the period Jan. 17 to Sept. 13, 2020, only one person per 85,000—or about 0.001%—later tested positive for SARS-CoV-2. Additionally, only 47 out of 278 people (17%) in that group with symptoms similar to SARS-CoV-2 had a measured temperature meeting the CDC criteria for fever.
Another problem with NCITs, Wright says, is that they may give misleading readings throughout the course of a fever that make it difficult to determine when someone is actually feverish or not.
"During the period when a fever is rising, a rise in core temperature occurs that causes blood vessels near the skin's surface to constrict and reduce the amount of heat they release," Wright explains. "And during a fever drop, the opposite happens. So, basing a fever detection on NCIT measurements that measure heat radiating from the forehead may be totally off the mark."
