Simple Blood Test Can Tell Whether Patients Will Suffer From ‘Long COVID’

A simple blood test for long COVID is on the horizon. Biological “fingerprints” can identify individuals with the debilitating syndrome, according to new research. This opens the door to the first accurate diagnosis of the mysterious condition. Sufferers complain it is hard to convince doctors of their disease.

Long COVID is an umbrella term for symptoms of the virus lasting more than 12 weeks. They range from fatigue, headaches, and breathlessness to fever and tummy pain. At least one fourth of patients have developed some form of long COVID, per research out of the University of California, Davis.

“We need a reliable and objective way of saying whether someone has had COVID-19,” says study co-leader Dr. Mark Wills of the University of Cambridge. “Antibodies are one sign we look for. But not everyone makes a very strong response and this can wane over time and become undetectable.”

The new technique is based on chemicals called cytokines that control blood cells. When released, the tiny proteins trigger the immune system’s T-cells to fight foreign invaders.

“We’ve identified a cytokine that is also produced in response to infection by T-cells and is likely to be detectable for several months — and potentially years — following infection,” adds Wills. “We believe this will help us develop a much more reliable diagnostic for those individuals who did not get a diagnosis at the time of infection.”

The discovery could revolutionize treatment by complementing existing antibody tests and identifying vulnerable individuals. It builds on a pilot study of 85 patients from the Long COVID Clinic at Addenbrooke’s Hospital in Cambridge. Blood samples were collected at the time of diagnosis and follow-up intervals over several months. Analyses identified a molecule known as a cytokine produced by T-cells in response to infection.

Like antibodies, the biomarker persists in the blood for a long time after infection. What’s more, a second type was found in patients with long COVID. It might even fuel the host of complaints. They also include muscle, joint- and chest pain, along with loss of smell or taste.

“Because we currently have no reliable way of diagnosing long COVID, the uncertainty can cause added stress to people who are experiencing potential symptoms,” explains study co-leader Dr. Nyarie Sithole, also from the Department of Medicine at Cambridge. “If we can say to them ‘yes, you have a biomarker and so you have long COVID’, we believe this will help allay some of their fears and anxieties.”

Patients generally feel abandoned and dismissed by healthcare providers and receive limited or conflicting advice. Between 27 and 33 percent of U.S. patients who had COVID-19, but did not need to be hospitalized later, developed some form of long-haul COVID, per UC Davis. About 33 percent of COVID-19 outpatients and 31 percent of hospitalized patients developed long-haul symptoms, according to research from the University of Washington.

A patient with asymptomatic or mild disease may not have taken a polymerase chain reaction (PCR) test, the gold standard for diagnosing COVID. Even antibody tests, which look for immune cells produced in response to infection, are estimated to miss almost one in three cases.

Dr. Wills and colleagues now plan to expand their cohort to 500 patients recruited from Cambridgeshire and Peterborough in England. By tracking them for up to 18 months post-infection, they hope to address several questions, such as if immunity wanes over time. This will shed light on whether those who have been vaccinated will need boosters to keep them protected.

“There’s anecdotal evidence patients see an improvement in symptoms of long COVID once they have been vaccinated — something we have seen in a small number of patients in our clinic. Our study will allow us to see how this biomarker changes over a longer period of time in response to vaccination,” says Dr. Sithole.

Increasing the number of participants and carrying out further work will enable the tests to be scaled and speeded up for clinical diagnosis. It may also show how the immune system responds to a coronavirus infection and why it triggers long COVID in some.

“One of the theories of what’s driving long COVID is it’s a hyperactive immune response. In other words, the immune system switches on at the initial infection and for some reason never switches off or never goes back to the baseline. As we’ll be following our patients for many months post-infection, we hope to better understand whether this is indeed the case,” says Dr. Sithole.

A reliable biomarker could also lead to the development of new treatments. Clinical trials require an objective measure. Changes in — or the disappearance of — long COVID-related cytokine biomarkers with corresponding symptom improvement would suggest a drug is working.

Fitness trackers provide conclusions related to COVID-19!
By Ask the Doctors • August 4, 2021

Dear Doctor: I had a bad case of COVID-19 last spring. It took a while, but I’m mostly OK now. The only thing is, the numbers on my Fitbit aren’t as good as they used to be, especially my heart rate. Is that because of COVID? How long until I’m back to normal?

Dear Reader: It didn’t take long for fitness trackers to evolve from their original purpose. They began as mechanical devices designed to collect basic information, like the number of steps taken and distance traveled throughout the day. Thanks to advances in tech, they quickly progressed to electronic data-collection systems.

Depending on the specific device you’re using, a fitness tracker can keep tabs on variables like distance, speed, direction and duration of movement, and even changes in elevation of the terrain. Through skin contact with an array of sensors, these devices can deliver information about a person’s heart rate while they’re active and while they’re at rest, and specifics about their heart rhythms.
Some are even equipped with sensors and software that the manufacturers say can flag potential heart issues.

A study we wrote about last year found that subtle changes in health data collected by fitness trackers were surprisingly reliable predictors that someone was about to come down with the flu.

The same predictive ability proved true with people who became ill with COVID-19.

Now, sensors and algorithms are offering up conclusions related to long-haul COVID. As many of you doubtless know, that’s the name for the array of ongoing symptoms that some people experience for weeks, and sometimes months, after they have recovered from the initial infection.

One of the authors of that flu study, along with other researchers in California and Michigan, has examined the fitness tracker data of 234 people who had tested positive for the coronavirus that causes COVID-19. The group they followed had been moderately to severely ill. For at least three months after an initial diagnosis, the researchers saw persistent physiological changes, including an elevated heart rate.

Because fitness trackers reveal patterns of movement, the researchers were able to identify changes to the individuals’ behavior, as well. This included a decrease in distance traveled each day and an increase in time spent sleeping.

Although similar changes were seen in a group of people who had non-COVID-19 respiratory illnesses, they resolved far more quickly.

COVID-19 has a wide range of effects. This is proving to be true of long-haul COVID as well. For people in the study who were ill with COVID-19, it took an average of 79 days for their resting heart rates to return to what they had been before they became sick.

Individuals whose illness was due to something other than COVID-19 saw their heart rates returned to normal just four days after their illness ended. For 14% of the COVID-19 group, a heart rate that was five beats faster than prior to their illness persisted for more than four months. We wish we had a better answer, but there’s no way to predict how long the after-effects of COVID-19 will last.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

https://connect.uclahealth.org/2021/08/04/fitness-trackers-provide-conclusions-related-to-covid-19/

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