What exactly defines a fever?

What exactly defines a fever?

For the purposes of symptom screening, it is important to clearly establish what body temperature is considered abnormal and warrants further examination. While it is widely understood and accepted that a fever is a sign that the body is fighting infection or illness, there is no universal agreement among some state public health authorities of what temperature constitutes a fever. 

“This is concerning because it adds entirely unnecessary complications,” said Dr. George Astrakianakis, international pandemic infectious disease policy expert and member of the Infectious Disease Council. “The CDC does not specifically ID what a fever is except in its rules for reportable illnesses, which is a distinct guidance from COVID-19.”

The CDC states that a person may have a fever if they “feel warm to the touch or give a history of feeling feverish.” Some define a fever as anything above 98.6 degrees F, while others state that a body temperature does not qualify as a significant fever until it reaches 100.4 degrees F. Other debates include how a temperature is measured, oral or otherwise. Screening for a fever is not possible without a clear, supported definition of what constitutes one. 

Based on the best available data and current research, the members of the Infectious Disease council agree that any body temperature, measured using an oral thermometer, and reading at or above 100 degrees F is considered a fever and worthy of greater scrutiny. A threshold lower than this may unnecessarily flag elevated temperatures that remain in a normal range; while a threshold higher than this may cause a screening tool to miss a temperature that falls in an abnormal range.

“For screening and compliance purposes, CastleBranch identifies 100 degrees F as the threshold for identifying fever. I agree with this approach,” said Dr. Douglas Grant, Registrar and CEO of the College of Physicians and Surgeons of Nova Scotia and member of the Infectious Disease Council. “While some regional variations exist for identifying fever, the CB threshold of 100 degrees F is consistent with accepted standards, supported by medical evidence, and clarifies all confusion.” 

Although a fever is not a symptom exclusive to the novel coronavirus, it is the most common symptom of COVID-19. A February study conducted by the World Health Organization states that of 55,924 confirmed COVID-19 cases in China, 87.9% of individuals reported a fever. As part of a comprehensive screening tool, a temperature reading may be used as a first step to determine if further examination is needed. While the term “fever” is not universally defined, 100 degrees F is accepted in the medical and infectious disease community as a body temperature that is abnormal and therefore warrants further examination and scrutiny.

written by Dr. Douglas Grant

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