As the country starts to reopen, one of the measures often put into place is the temperature check. A temperature is a single data point in time and cannot stand on its own to rule in or rule out COVID-19 or any other infectious illness. It can be a symptom of an infection and that is all the weight that can be assigned to it. We cannot identify the cause of the infection based solely on the temperature, but it is a starting point.

1)  How is the temperature check being used? In the medical community, it can be on the honor system—each employee is responsible for taking their own temperature twice a day—and base their ability to work on that, PLUS other possible COVID-19 symptoms they may have. Others have a staff member at the door of the facility taking the temperature of each staff member walking through the door and logging it along with the person’s name, and YES/NO answer to several screening questions. In other industries, it may be one person taking the temperature of each worker on arrival to the job site and each employee is responsible for daily screening themselves. Yet others are deploying thermal scanners at job site entries. (Thermal scanners are a contentious topic in and of themselves that I’ve written on previously.)

2) What does an elevated temperature >/= 100.0F mean? It simply means the temperature of THAT one measurement—oral, rectal, temporal, tympanic (ear), or axillary (under the armpit)—is above the normal standard of 98.6F.  

• • • WHAT is normal? The average normal body temperature is accepted as 98.5F (37C).  Many studies show normal can actually have a wide range from 97-99F (36.1-37.2C).  GENERALLY a temperature over 100.4F (38C) most often indicates presence of fever caused by infection or illness. What constitutes a “fever” as it pertains to COVID-19? The CDC has changed the recommendation of what constitutes fever from 100.4F to 100.0F. “Fever” is either measured temp >/= 100.0 or subjective fever. This change translates down the decision tree and thresholds for screening and discussing COVID-19 symptoms with the patient and when staff members take temps at home to assess their ability to work.
    • WHERE was the temperature taken? Tympanic temperature is 0.5-1F higher than oral temperature, and armpit temperature is usually 0.5-1F lower than oral temperature. The most accurate (but clearly the least likely to be utilized anywhere even in the hospital) is rectal temperature. 
    • WHO is taking the temperature? A medically trained person who knows the device they are using and is using it according to manufacturer’s directions is most likely to be accurate.  Someone without familiarity of the thermometer or how to use it may not yield an accurate reading.  
    • WHEN is the temperature taken? Take your temperature in both the morning and the evening. Body temperature can vary as much as 1F (0.6C) during the day. Wait at least 30 minutes after you drink cold or hot liquid, eat, or smoke if you take a temperature by mouth.  Wait at least 15 minutes after activity or exercise, or if coming in from the cold or from the heat.

A diagnosis of any disease, let alone COVID-19, cannot be made based on a single temperature. An endoscopy center I know is having patients keep a temperature log for 14 days prior to their elective colonoscopy or endoscopy procedure and that log is reviewed by the nurse who is admitting the patient prior to bringing the patient back for the procedure. Doing this, at least 14 data points are available to review for a trend, but even that is only one symptom—fever.  

Additional data points need to be considered including other symptoms as per the CDC including cough, shortness of breath or difficulty breathing, sore throat, chills, muscle pain, new loss of taste or smell.  Even these symptoms are not exhaustive as some patients have gastrointestinal distress such as abdominal pain, nausea, or diarrhea.