Covid-19 screening: are forehead temperature measurements during cold outdoor temperatures really helpful?

Background: Body temperature control is a frequently used screening test for infectious diseases, such as Covid-19 (Sars-CoV-2). We used this procedure to test the body temperature of staff members in a hospital in Tyrol (Austria), where the Covid-19 disease occurred in March 2020. The hospital is located in a mountain area at 995 m above sea level with low outdoor temperatures during early spring season. Under these conditions, we analyzed whether forehead temperature control offers a sufficient screening tool for infectious diseases.

Methods: Forehead temperature of 101 healthy male and female employees was measured with an infrared thermometer directly after entering the hospital (0 min), followed by further controls after 1 min, 3 min, 5 min and 60 min. We also tracked the outside temperature and the temperature at the entrance hall of the hospital.

Results: Complete data of body temperature were available for 46 female and 46 male study participants. The average forehead temperature measured directly after entrance to the hospital was the lowest (0 min) 33.17 ± 1.45 °C, and increased constantly to 34.90 ± 1.49 °C after 1 min, 35.77 ± 1.10 °C after 3 min, 36.08 ± 0.79 °C after 5 min, and 36.6 ± 0.24 °C after 60 min. The outside temperature ranged between -5.5 °C and 0 °C, the indoor temperature had a constant value of 20.5 °C.

Conclusion: Our results indicate that forehead infrared temperature control is not an appropriate tool to screen for infectious disease directly at the entrance of a building, at least during early spring season with cold outdoor temperatures.