In a perspective piece published in Open Forum Infectious Diseases, the authors questioned the most appropriate temperature cutoff to define a fever and the best method for assessing coronavirus disease 19 (COVID-19) fevers.

In March 2020, both the United States Department of Health and Human Services (DHHS) and the Centers for Disease Control and Prevention (CDC) recommended that individuals with a temperature greater than 100.4°F self-quarantine for 14 days. However, research suggests that less than half of patients who test positive for COVID-19 had temperatures greater than 102.2°F (9%) or 100.6°F to 102.2°F (34%).

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Furthermore, the term “body temperature” is vague, as temperature varies by anatomical site. In general, axillary temperatures are lower than oral temperatures which are lower than rectal temperatures.

Additionally, several biological features alter temperature including gender, ethnicity, and circadian rhythm. Environment factors such as makeup, sweat, distance between device and subject, ambient air temperature, and humidity can alter noncontact infrared thermometer accuracy.

Since the beginning of the COVID-19 pandemic, noncontact infrared thermometers have been used in clinical and public settings due to the ability to assess temperature while maintaining physical distance. However, among 46,000 travelers screened by infrared thermometers at airports in the United States, only a single COVID-19 infection was detected.

Overall, current data suggest that COVID-19 fever cutoffs should be reevaluated, the paper authors concluded. Additionally, because 40% to 45% of COVID-19 infections are asymptomatic, any mass temperature-screening program is likely to fail.

The authors speculated that perhaps a more prudent mass-screening program should include innovative public health surveillance tactics involving group testing or data from wearable devices. However, current noncontact infrared temperature screenings for COVID-19 have not been successful.


Wright WF, Mackowiak PA. Why temperature screening for covid-19 with non-contract infrared thermometers doesn’t work. Open Forum Infect Dis. Published online December 14, 2020. doi:10.1093/ofid/ofaa603.

This article originally appeared on Infectious Disease Advisor