Published: 04-06-2021 15:44 | Updated: 07-06-2021 12:26

Self-monitoring with smartwatch ECG in a new Long COVID triage study

A hand holding a smartwatch
ECG measurement with a smartwatch. Photo: Sebastian Westerling.

By end of 2021 Sweden will probably have up to 100,000 Long COVID patients and globally there will be more than 20 million. These estimates are based on current rates of infection and that 10% of patients have longer term symptoms after a COVID-19 infection.

The healthcare system urgently needs affordable at-home health monitoring methods to evaluate the need of medical care for those affected.  Karolinska Institutet (KI) is therefore launching a study, headed by researchers at the Department of Global Public Health to determine if a smartwatch ECG test can be used as a triage method for identification of individuals with Long COVID that require a more active follow-up and medical care.


About ten percent of COVID-19 patients fulfil the criteria of Long COVID, defined as having symptoms lasting more than 3 months after a COVID-19 diagnosis.   Most cases are currently considered to be either due to residual cardiac or respiratory inflammations or that the virus is causing autoimmune reactions. It is essential to develop new methods for monitoring of symptoms for the healthcare system to adequately manage these patients. The need for more effective monitoring methods is especially pronounced in low- and middle-income countries, where the healthcare system has limited resources.

Novel automated at-home monitoring methods are greatly needed

The aim is to find novel at-home measurable Long COVID biomarkers and new methods to better monitor and assess the need for more active care. According to Dr. Johan Lundin, Professor of Medical Technology at KI and Principal Investigator of the study, there is a great need for novel self-monitoring methods. The project uses a smartwatch electrocardiogram (ECG), a smartphone app to guide the user and cloud-based analytics with artificial intelligence (AI) in an area where there are very few solutions yet.

Smartwatch and app
Smartwatch and app for self-monitoring. Photo: Illustration: Emma de la Chapelle

The at-home self-monitoring tests are done with 30 seconds ‘ECG’ smartwatch recordings

According to the study hypothesis the test can detect deviations from the normal synchronization between heart rate and respiration and through that identify more severe forms of Long COVID. The test is carried out with smartwatch ECG recordings (either an Apple Watch or a dedicated low-cost ECG enabled smartwatch entitled the Vagus Watch) which both use a specially designed app (‘VAGUS ECG’) available for the main smartphones operating systems (iOS or Android). A cloud-based AI analysis detects subtle changes in the synchronization between heart rate and respiration, which are known to occur in association with Long COVID. The primary aim is to establish whether persistent cardiac or respiratory inflammation is the most likely cause for participants’ Long COVID symptoms or if the symptoms are more likely due to other causes, such as inflammatory processes in other organs, autoimmune diseases or mental issues such as depression, anxiety or chronic stress.  

The study participants are planned to be recruited via Swedish Long COVID clinics. In addition, reference groups are recruited worldwide among smartwatch (Apple Watch) users.   For the reference group of volunteers, medical records such as results of COVID-19 tests, blood tests or medical scan reports are planned to be collected. The study data collection period is 3 months.

Available position

The project is currently recruiting a postdoctoral researcher. The recipient of the position is expected to coordinate the research project and assist in the recruitment of other researchers to be affiliated with the project. If you are interested, please visit Jobs at KI.


Funding and disclosures

The British company Vagus Health contributes by donating 100 Vagus ECG smartwatches, cloud diagnostics and data resources for the study. Vagus Health Ltd is a Cambridge (UK) based bioelectronics company founded in 2017 and employs a team from Finland, Sweden and the UK.   The name of the company comes from the vagus nerve which is the company’s focus for greater understanding of the connections between the autonomic nervous system and health.

More information

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Johan Lundin