Fever-Tracking Wearables Could Help Identify Early COVID-19

Oura ring on a white background.


Key Takeaways

  • Temperature-sensing wearable devices can track body temperature over time.
  • Continuous body temperature monitoring can indicate the onset of fever more accurately than single time-point temperature readings.
  • The study tracked 50 individuals who wore a smart ring during COVID-19 infection and recovery.

Imagine that you're feeling fine, but when you glance at your wearable device, you notice that your temperature is much higher than your average for that time of day. The spike in your body temperature could indicate you're developing a fever. The information might prompt you to schedule a COVID-19 test or look more closely at your health.

A new study, published on December 14 in the journal Scientific Reports, has assessed the feasibility of using smart devices for continuous fever monitoring. The authors theorize that temperature-sensitive technology could have public health benefits for monitoring everything from COVID-19 to food poisoning.

“The potential here is to have a smart, relatively real-time fever detection system that allows public health to start having, essentially, weather radar to see where there are illnesses emerging across the country or across the world,” Benjamin Smarr, the paper’s corresponding author and a professor in the Department of Bioengineering at UC San Diego, tells Verywell. 

The researchers analyzed data from more than 50 COVID-19 survivors who had consistently worn a wearable ring created by Oura, a Finnish startup company.

The goal was to develop an algorithm that could detect the onset of symptoms like fever, cough, and fatigue, which are characteristic of COVID-19. The findings are the first from TemPredict, a study of more than 65,000 people wearing the Oura ring.

How It Works

Oura's ring tracks several health metrics, including heart rate, respiratory rate, and levels of activity. It's also one of the few wearable devices that monitors body temperature.

The Oura ring has sensors that record the temperature of blood flowing through the arteries in the wearer's finger. Your internal temperature changes throughout the day depending on where blood is flowing in the body.

Benjamin Smarr

The potential here is to have a smart, relatively real-time fever detection system that allows public health to start having, essentially, weather radar to see where there are illnesses emerging across the country or across the world.

— Benjamin Smarr

At night when you're asleep, blood flows more easily to your body’s periphery— including your fingers—making them warmer. During the day, more blood flows to the core to help your body digest food or keep you active, which means the arteries in your fingers will carry less blood and be cooler. 

Smarr says that the TemPredict team chose to collaborate with Oura because it allows public researchers to access and analyze data from users who consent to share it.  

The study found that 76% of the subjects indicated fever as a symptom of their illness. That result is on par with the reported national average of people who report fever during the course of COVID-19 infection.

The majority of the participants exhibited abnormal body temperatures before they developed other symptoms, suggesting that elevated body temperature could be a predictor of illness. 

A More Reliable Method

Checking temperatures has become a common practice during the COVID-19 pandemic. Restaurants, stores, and public transportation systems may require a quick temperature check to identify people who are showing symptoms.

When using this method, each person’s temperature is compared to a broader population or accepted temperature threshold to determine whether they have a fever. The method also only provides information on a single point in time.

Smarr says that the variation in blood flow throughout the day means that testing a person's temperature at a single point in time will be less reliable than monitoring it consistently. 

“It lets us see those temperatures that are hot for the time of day they’re at, and not just hot for everybody on Earth,” Smarr says. “That makes it much more capable of detecting these fevers, even across lots of different people.” 

The clinically accepted threshold for fever is 100.3 degrees Fahrenheit. However, Smarr says that the standardized measurement may not reflect the temperature at which all people experience fever. 

“We hear a lot about asymptomatic cases and people without any signs of illness. Their bodies may very well show signs of illness because we see those signs with our sensor data," Smarr says. "They may simply not be cognizant of it—they may not know, or they may just not report it.”

The use of an individual monitoring system, like the Oura ring, lets a person track their personal temperature patterns and notice when the numbers are off. It also lets them look at their temperature alongside other health measures.

Not a Diagnosis

Researchers say that several health conditions could be tracked using temperature-monitoring technology. For example, people with the flu and food poisoning often experience fevers.

Albert Titus, a professor of biomedical engineering at the University of Buffalo, tells Verywell that it could be useful for people to stay attuned to their body temperature and how it changes. If they notice a spike in temperature, however, they will have to assess other health metrics to pinpoint the cause. 

“The value is in the trends in combination with other data and information that makes this potentially useful while recognizing that at this point it’s also not diagnostic of a particular disease, but indicative of an overall health change,” says Titus, who is not affiliated with the study.

The onus lies with the wearer to make sure that they are paying attention to the data gathered by their smart device and taking steps to address the findings, if necessary.

Future Research

The authors emphasize that the paper is merely a "proof of concept" and a starting point for more in-depth research.


Future research could also address the issue of diversity: Of the 50 study subjects, 81% identified as white. Smarr says that future algorithms and research efforts will need to include a more diverse array of study subjects to ensure accurate societal representation.

“One of the big challenges for smart public health is making sure that when we develop these complex technologies," Smarr says, "we aren’t just letting them grow on top of wealthy people of means, but that we’re really thinking about how we’re ensuring that these technologies are fairly representing everybody in society."

Socioeconomics and Privacy

Another factor is socioeconomic. Wearable devices can be expensive, and the people who use them may not represent a population as a whole.  

“An issue with wearables is often how accessible they are to the general population because of cost and technical support, etc.,” Titus says. “Are you only getting a sampling of data from people who can afford it or are gadget-interested in early adopters?”

To further understand the implications of wearable technology for public health, Smarr says that it will be important for researchers to have access to data from the companies who are producing it. To do that, users will have to trust that their health information will be safely used, and large companies will have to become more willing to share data with public health researchers. 

“I’m hoping this is an indication to those larger players that there is a lot they could be doing,” Smarr says. “They’re in a position to really make a difference and that maybe users should expect that of them.”

What This Means For You

Your body temperature changes throughout the day depending on your level of activity and blood flow. Continuously tracking your body’s temperature patterns could help you notice when it spikes, potentially indicating a fever.

Experts say that this is a more accurate way of detecting fever than comparing your body temperature to the national average. If you use a wearable like the Oura ring that can help you keep track of your temperature, it might be able to offer some insights.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

2 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Smarr BL, Aschbacher K, Fisher SM, Chowdhary A, Dilchert S, Puldon K, et al. Feasibility of continuous fever monitoring using wearable devicesSci Rep. 2020;10(1):21640.

  2. UCSF Osher Center for Integrative Medicine. $5.1M Awarded to the TemPredict Study Directed by Ashley Mason, Ph.D.

By Claire Bugos
Claire Bugos is a health and science reporter and writer and a 2020 National Association of Science Writers travel fellow.