Fever checks have widely become the first level of coronavirus detection as businesses, stores and schools try to reopen, but a new study cautions that relying on them as a single screening tool could lead to a false sense of security.
Fever is generally the first symptom of a coronavirus infection, according to a study from the University of Southern California, followed by cough, nausea, vomiting and lower gastrointestinal symptoms, such as diarrhea.
For the study, researchers used WorldHealth Organization data, which included information on nearly 60,000 confirmed cases of COVID-19, to model the order of symptoms. Limitations of the study, published last week in a public health journal, include that the cases were almost all from China during the early days of the pandemic, before other types of symptoms were recognized.
While a temperature check can detect people who are showing symptoms, there are a significant number of people who could be contagious that don’t develop a fever, said study co-author Peter Kuhn, a professor of biological sciences, medicine and engineering at USC.
A temperature of 100.4 F is considered a fever by the Centers for Disease Control and Prevention.
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With more than 21 million confirmed COVID-19 cases worldwide, public health officials have learned that the infection can cause a wide range of symptoms, from barely noticeable sniffles and headaches to difficulty breathing and chest pain. The CDC currently lists the following possible symptoms, but says there may be others:
Fever or chills
Cough
Shortness of breath or difficulty breathing
Fatigue
Muscle or body aches
Headache
New loss of taste or smell
Sore throat
Congestion or runny nose
Nausea or vomiting
Diarrhea
Studies have shown that children are more likely to have milder symptoms, which could be mistaken for a different illness. A new loss of smell and taste is a common early symptom for milder cases, and is more common among younger patients and women.
Symptoms can appear anytime between two to 14 days, although about five to six days after exposure is the average. While many people never show signs of infection, even those who eventually do become symptomatic could spread the disease for days prior to developing a fever, said David Paltiel, a professor at the Yale School of Public Health.
“If you’re using signs and symptoms as a basis for moving ahead, it’s like the fire department waiting until a house has burned down before springing into action,” said Paltiel, who published a study in July on bringing college students back to campus in JAMA Network Open.
Linda Carroll is a regular health contributor to NBC News and Reuters Health. She is coauthor of “The Concussion Crisis: Anatomy of a Silent Epidemic” and “Out of the Clouds: The Unlikely Horseman and the Unwanted Colt Who Conquered the Sport of Kings.”