Why temperature measurement is not objective
Non-contact thermometers measure the temperature of people at airports, at social events. Rosportebnadzor recommended this method to employers to control the temperature of workers. Is it effective?
Expectations from non-contact temperature measurement have not been met in practice. For example, by February 26, 2020, about 46 thousand passengers were checked at US airports. Only one has been found to be infected. By April, their number increased to 15.
Another problem raised by the authors of the article in the Open Forum Infectious Diseases is the sensitivity of non-contact temperature measurement to a variety of external factors. Results may vary depending on which part of the body the temperature is measured over, the ambient temperature, and more. At the same time, the most accurate temperature measurement methods are not suitable for mass screening.
Non-contact temperature measurement can be inaccurate, even if a person has a fever. “An increase in core temperature can cause vasoconstriction in the skin, resulting in less heat generation,” says William F. Wright of Johns Hopkins University School of Medicine, co-author of the article.
How is screening done?
In the conclusions of their article, the scientists write that when developing programs for screening COVID-19, it is necessary to take into account all the factors that make non-contact temperature measurement inaccurate.
The authors provide examples of strategies that could improve the identification of sick people. In their opinion, it would be possible to lower the target temperature for screening (that is, to make it below 38 degrees). This can be especially true for screening the elderly and immunocompromised people.
Another screening option is group testing. In this case, we are not talking about measuring the temperature. A group of people need to take nasopharyngeal swabs for PCR, but they should not be examined individually, but together. If the test is negative, the entire sample of people is considered not infected.
Also promising methods, scientists consider the study of drainage water for coronavirus and the use of “smart” wearable thermometers connected to a smartphone.