Why has "37.5℃ Fever" become an indicator of COVID-19?
Why has "37.5℃ Fever" become an indicator of COVID-19?
  • Doctor Han Dong-ha of korean medicine (desk@k-health.com)
  • 승인 2020.04.29 07:58
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Doctor Han Dong-ha of Oriental Medicine (Director of Han Dong-ha Oriental Medicine Clinic)
Doctor Han Dong-ha of Korean medicine(Director of Han Dong-ha Korean Medicine Clinic)

As the coronavirus spread, infrared thermometers have been installed in entrances of large buildings where many people gather together. Through this process, every single visitor’s body temperature is measured. After this temperature is identified, whether the visitor is allowed to enter the area or not is determined by the standard of 37.5℃. This light fever that anyone may have can end up holding us back.

The range of normal body temperature is under 37℃. However, due to age and environment, there is a difference in temperature of an average of 0.5℃ for different individuals. For younger individuals, normal body temperature is relatively higher. For instance, 38℃ is also included in the range of normal body temperature for infants younger than 2-year old. However, for 11-year old children and adults after, 37.5℃ is normal body temperature. Although the temperature may differ depending on the time of measurement, it is the highest between 4~6 in the afternoon.

Temperature also differs for different body parts. If they are listed in order from highest to lowest from being measured with a traditional mercury thermometer, they are ▲rectal temperature (36.6~37.9℃) ▲ear temperature (35.8~37.5℃) ▲oral temperature (35.5~37.5℃) ▲armpit temperature (35.7~37.3℃). Because the rectum is close to the core body temperature, the rectal temperature can be considered as the most accurate temperature. Due to such reasons, there may be cases in which the normal body temperature can go over 37.5℃. However, with the oral temperature as the general standard, if the oral temperature goes over 37.5℃, a person can be judged to ‘have a fever’.

Temperature is also measured differently by different thermometers. Although mercury thermometers are the most accurate, electronic ear thermometers have also been used very much recently. However, the problem is the fact that the measured temperature easily changes depending on the direction of injection. Electronic ear thermometers, in particular, measure different temperatures for every thermometer and because the margin of error is also wide, careful consideration must be made.

Recently, due to the COVID-19 pandemic, no-touch thermometers that measure forehead or wrist areas have also been widely used. However, such methods may also result in lower temperatures because body heat is lost due to vaporization of moisture and sweat on the areas of which temperature is measured.

Generally, for fevers, we tend to place our hands on our foreheads to measure the temperature. However, even high temperatures of around 39℃ can be felt as normal for 40% of individuals. Because the skin temperature of our palm can be high, the temperature we feel can seem lower than it is. If no thermometer is available, it is more accurate to measure body temperature with the back of the hand than the palm and touching the back of the neck behind the ears can also be a good method to measure temperature.

Fever shows a unique pattern depending on the type of infection. For instance, for colds and pneumonia, fever repeatedly goes up and down. This fever pattern is the same for COVID-19 as well. For sicknesses caused by a bacterial infection such as typhoid and meningitis, the fever slowly rises and continues for the whole day. If an individual gets infected with malaria, the fever goes up and down in terms of one or two days and if infected with tuberculosis, light fever may occur only at night.

Therefore, rather than blindly consuming a fever-reducing medicine whenever there is a fever, it is also important to first observe how the fever occurs if that is, the fever is at a bearable level. However, in case of a high fever of 39~40℃, because drowsiness can occur and for children, convulsion can happen, there is a need to take a fever-reducing medicine for emergency purposes.

Since fever can be an indicator of the degree of inflammation resulting from immune response, it is desirable to let the fever reduce naturally as the sickness symptoms get better.

As aforementioned, in the case of disease from bacterial infections, the clinical standard of fever is when the temperature goes over 37.5℃. However, even if the body temperature increases and exceeds 37.5℃, the heat may not be felt depending on the individual. But because it is rare for the body temperature to go over 37.5℃ except for some healthy individuals, 37.5℃ has become the standard of fever for the infection of COVID-19.

I also measure the body temperature of my patients from time to time. Although thankfully, there were no patients that showed symptoms of fever recently, how would have I responded if the measured temperature went over 37.5℃? I would have probably become anxious and worried, repositioned my mask, and asked the patient questions like when the fever started, whether there were other symptoms, and whether he visited specific places in Korea. The temperature of 37.5℃ has become the indicator of the infection of the coronavirus and the reasons for that seem to be very clear.



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