Do temperature checks really catch COVID infections? Depends on your age, experts say

·3 min read

Many businesses, offices and events are still depending on temperature checks to detect coronavirus infections among the seemingly healthy. But fevers aren’t always a part of the COVID-19 package, especially among older adults.

A better alternative: measuring oxygen levels in the blood with a noninvasive, painless and inexpensive device called a pulse oximeter, according to two nursing professors from Washington State University.

The pair highlights scientific evidence that shows older adults have lower core body temperatures than younger adults. They also note that common signs of COVID-19, such as body aches or fatigue, may be blamed on age rather than potential sickness, increasing the likelihood a real infection will be dangerously dismissed.

What’s more, coronavirus patients of all ages sometimes experience “silent hypoxia.” It occurs when people are unknowingly oxygen deprived as they remain alert and breathe normally, Catherine Van Son, an associate professor of nursing, and clinical assistant professor Deborah Eti wrote in an opinion article published last month in the journal Frontiers in Medicine.

Using pulse oximeters to detect what Van Son and Eti call “asymptomatic hypoxia” can prevent infections from progressing, initiate treatments sooner, help patients avoid invasive procedures such as mechanical ventilation and free up scare health care resources.

“Symptom-based screening for COVID-19 is a less than precise endeavor, and data being collected during this pandemic is finding that temperature and self-report of exposure and/or symptoms are missing more than 50% of infected individuals,” the professors wrote. “Decreasing fever thresholds and adding AH screening via a pulse oximeter to routine vital signs is not an unrealistic nor cost prohibitive goal.”

“Intervening sooner could potentially decrease mortality rates, before the infection progresses to a point of a fever, and the COVID-19 battle is lost,” they wrote.

Generally, about 98% of COVID-19 patients develop a fever along with other symptoms, but only about 30% of older adults with serious infections get a mild or no fever. With that being said, older adults make up the majority of coronavirus-related hospitalizations, intensive care admissions and deaths.

A temperature is considered feverish once it reaches 100.4 degrees Fahrenheit, but studies have found that older adults’ normal core body temperature is lower than younger adults, sometimes as low as 94 degrees Fahrenheit. (The average human body is about 98.6 degrees Fahrenheit, although more recent studies suggest they run a bit cooler).

For example, a study of 2,410 patients aged 65 and older hospitalized with the flu found a lower temperature threshold of 99 degrees Fahrenheit detected 78% of infections, whereas a threshold of 100 degrees Fahrenheit caught just 57% of flu cases.

“Therefore, the objective measure of a temperature and the threshold of 100.4 F as a fever indicator does not provide a sufficient indicator of infection in older adults and may delay the diagnosis and treatment for COVID-19,” Van Son and Eti wrote.

Other symptoms such as changes in cognition, weakness, shortness of breath and coughing “may be dismissed as a normal part of aging.”

And in many instances, dismissed cases of silent hypoxia among older adults may delay care. Ensuring this group has pulse oximeters on hand could catch infections at home or in community living settings before their disease progresses and hospital admission is needed, the pair suggests.

“The absence of shortness of breath in an older adult should not be considered to be a good sign,” the professors wrote. “In these patients, pulse oximetry is an important means to improve COVID-19 outcomes.”

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