Could a blood test diagnose long-Covid? Study finds sufferers have distinctive differences in their cells

Blood tests of people reporting to suffer from long Covid show people who have the condition have distinct biological differences from those who do not. 

The report offers the first bit of evidence to show people suffering from the hard-to-define condition have noticeable differences in their biology compared to non-sufferers.

Results from the first-of-its-kind study mark major progress in diagnosing and treating the puzzling condition, which an estimated nine million Americans live with. 

Long Covid consists of a constellation of symptoms that persist after someone has recovered, including unrelenting fatigue and brain fog. Patients are often dismissed by doctors who think it’s all in their head or another condition entirely.

Researchers at Yale University and Mount Sinai Hospital relied on artificial intelligence to analyze hundreds of blood samples from people with and without long Covid. The biological differences they identified suggest symptoms could be treated with experimental medicine.

Long Covid is estimated to affect between nine and 20 million Americans. It is difficult to diagnose as most clinical diagnostic tests such as urinalysis and X rays return normal. But the latest findings suggest blood tests could be useful in identifying possible treatments for symptoms 

Identifying specific biomarkers of long covid serves as a major win for sufferers who have repeatedly being dismissed by doctors who believe the symptoms are all in their heads

Their findings could pave the way for simple blood tests to be able to diagnose long-Covid, which has historically been difficult because clinical testing and X-rays typically return normal results. 

The study, led by Dr David Putrino, a physical therapist and rehabilitation expert at Mount Sinai, included an analysis of more than 270 blood samples from people who had fully recovered from a confirmed case of Covid, those with active long-Covid symptoms for at least four months after a confirmed COVID-19 infection, and those with no prior Covid infection.

Dr Putrino said: ‘These findings are important—they can inform more sensitive testing for long COVID patients and personalized treatments for long COVID that have, until now, not had a proven scientific rationale.’

The analysis included samples that were taken between January 2021 and June 2022. It relied on both blood testing as well as a thorough questionnaire for participants to detail their symptoms, quality of life, and medical history.

Some of the biomarkers the authors of the groundbreaking study identified included abnormal activity of a certain kind of immune cell called T cells.

The malfunctioning of these cells can lead to chronic inflammation thought to be behind a slew of long Covid symptoms ranging from fatigue and joint pain to cognitive issues.

Researchers also found that, compared to non-long Covid sufferers, people with symptoms had about half the amount of cortisol, the body’s main stress hormone.

Not enough of this hormone, among other effects, leads to fatigue trouble falling asleep at night and waking up in the morning.

Finally, the team identified that the common Epsteine-Barr virus had been lying dormant in long-Covid sufferers and then was reactivated.

This virus causes mononucleosis, commonly known as mono, and is believed to contribute to many long Covid symptoms.

Dr Akiko Iwasaki, a biologist at the Yale School of Medicine and co-author of the study, said: ‘We are excited to see such clear differences in the immune phenotypes in people with and without long COVID.

‘These markers need to be validated in larger studies, but provide a first step in dissecting the disease pathogenesis of long COVID.’

The machine learning algorithm they used was able to distinguish individuals with long Covid from those without with a 96 percent accuracy.

Dr Putrino added: ‘This work is so exciting because it is one of the first to show us clear, measurable differences in blood biomarkers of people with long COVID compared with people who recovered fully from an acute infection and a group of people who have never been infected with SARS-CoV-2.

‘These findings show us that people with long COVID are living with a disease process that is observable using the blood testing protocols laid out in the study, but also varies from patient to patient depending on their specific medical history.’