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3 April 2020updated 26 Jul 2021 7:24am

Could your smartphone detect early signs of coronavirus infection?

As the government is criticised for its slow rollout of coronavirus testing, companies that make wearable tech are rushing to adapt their devices to detect Covid-19.

By Samuel Horti

In 2009, Fitbit released its first wearable device, a wristband that measured steps and estimated calories burned. This week, it unveiled the Fitbit Charge 4, a smart-watch that measures heart rate, senses the concentration of oxygen in the blood and tracks a user’s runs via GPS.

The wearable tech market has ballooned in recent years, in part because of the public’s desire to better understand and monitor their bodies, and Fitbit is not alone in focusing on health. The latest Apple Watch checks for atrial fibrillation, while Omron’s £500 HeartGuide blurs the line between smart-watch and blood pressure monitor. And now wearable tech companies are turning their efforts to the coronavirus pandemic.

Finnish start-up Oura has handed 2,000 of its smart rings, which measure heart rate and body temperature, to front-line healthcare workers in San Francisco, and researchers at the University of California are studying whether the devices can reliably detect symptoms of Covid-19, such as fever.

Meanwhile, a team at Central Queensland University Australia is testing whether a fitness wristband from Boston-based firm Whoop that tracks breathing rates can recognise the infection. The study is measuring respiratory patterns in volunteers that have self-diagnosed with Covid-19. Professor Greg Roach, the university’s head of sleep and circadian physiology research, has said the device “may be able to provide insights into the health implications before, during and after suspected cases of Covid-19”.

Wearable tech firms often make bold healthcare claims without robust science to back them up. A 2017 study from Rush University Medical College and Northwestern University’s Feinberg School of Medicine found that tech promising to help users sleep better often gave inaccurate readings, and that wearing the devices had worsened insomnia. But Covid-19 has put research into overdrive and anything that helps the public better understand their health, self-isolate when necessary, and slow the spread of infection might help.

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UK doctors seem open to the idea of patients using wearable devices, including smart-watches that monitor pulse rate, to track their health during the pandemic. Dr Asif Munaf, recently promoted to the role of NHS consultant, explains that elevated heart and breathing rates indicate “you’ve potentially got signs of an infection, which in this climate [could be] Covid-19”. Quantifiable data from wearable tech, in combination with other symptoms, can give patients an objective measure of their health, he says. “It’s hard to say ‘I feel better today than I did yesterday’, because that’s very subjective, but you can make it objective by looking at your heart rate.”

Dr Giuseppe Aragona, a GP and medical adviser to online pharmacy Prescription Doctor, admits many healthcare professionals are sceptical about the accuracy of wearable tech, but that “a growing number of physicians have embraced consumer healthtech products”. “In regards to the Covid-19 outbreak… body temperature sensors would be more reliable than [patients] simply putting their palms to their foreheads and trying to determine whether they have a fever if they don’t have access to a thermometer.” Early warning signs might prompt patients to seek advice from a doctor or self-isolate, he says.

But even if new research shows wearable tech to be effective in detecting Covid-19, it may be of limited use. These devices can’t monitor many of the common signs of the disease, such as persistent cough, headache or loss of smell. And as Dr Aragona points out, the tech might be too advanced for many older, high-risk patients, and too expensive for widespread ownership, “therefore having a limited impact on overall public health” (Oura’s ring costs €314 (£277), Whoop’s band is only available via a €25/month subscription service). 

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But what if researchers could harness smartphones, which are far more ubiquitous, to detect Covid-19? Phones are increasingly being used to monitor the progression of other diseases: a pan-European consortium of academics and doctors called i-Prognosis, which includes researchers from King’s College London, is currently trialling a system to identify Parkinson’s disease early by monitoring phone use and typing patterns, for instance. 

London-based healthtech firm Medopad hopes to do the same for Covid-19. Chief executive Dan Vahdat says his company has already built clinically certified tech that can measure heart rate using a smartphone camera –  echoing the pulse sensors that are on some phones. The method, known as photoplethysmography (PPG), measures subtle colour changes in a fingertip under a bright light – in this case, a phone camera’s flash.

Medopad is currently trialling whether respiratory rate can be measured in the same way, in partnership with an unnamed UK clinic. The trial involves using a smartphone to measure breathing patterns in patients with Covid-19 and other viral infections. The company is also testing whether a smartphone placed on a patient’s chest can accurately record both their breathing patterns and heart rate. “Of course, we have to clinically validate it, otherwise everything we’re saying is hypothetical,” says Vahdat. 

Naturally, readings from a phone cannot be looked at in isolation. Relying on one metric alone, such as heart rate, could create a “deluge of worried patients”, warns Dr Munaf, which could overload an already-stretched healthcare system. Devices or apps that are not clinically approved might not give accurate readings, and users would have to understand that any measurements must be compared to their own particular baselines. A resting heart rate of 80, for example, might be normal for some people, but high for others. Educating the public sufficiently to understand their own readings could be difficult.

But politicians are looking at anything that might help. The NHS is currently in talks to deploy an app that traces the close contacts of those carrying the virus and advises them to self-isolate, according to a  31 March report in the Guardian. Vahdat says several governments have expressed interest in a joint project between Medopad and Johns Hopkins University in Baltimore, in which researchers are developing an app to tell patients their chances of requiring hospitalisation or ventilation should they catch the disease. The app will include a lifestyle questionnaire and may involve users inputting vital signs. “By personalising the risk assessment to you, we’re hoping to drive better adherence to public guidelines,” Vahdat says. If users opt in to sharing their data centrally, they will also help governments gain a better picture of the risks within their country, he adds.

If the UK can meet its target of testing 100,000 people a day, then the use of smartphones and wearable tech in detecting signs of Covid-19 may become obsolete. But until then, the public will be searching for tools to better monitor their health and detect signs of the virus. Perhaps they’ll find one in their pocket.

Samuel Horti is a freelance journalist who covers politics, culture and gaming