Sep 25, 2023 - Health

Scientists take "decisive step" in blood testing for long COVID

Coronavirus molecule

Illustration of coronavirus molecule. Photo: CDC/API/Gamma-Rapho via Getty Images

Patients suffering from long COVID have distinct immune and hormone imbalances compared to those without, according to a new study published in the scientific journal Nature.

Why it matters: More than three years since the COVID-19 pandemic began, the breakthrough offers concrete scientific evidence of a complex condition that scientists have struggled to understand.

  • "This is a decisive step forward in the development of valid and reliable blood testing protocols for long COVID," David Putrino, one of the study's authors and the director of rehabilitation innovation for the Mount Sinai Health System, said in a press release.

Between the lines: While no blood tests for diagnosing long COVID currently exist, the study's results suggest it may be possible to develop one in the future, NBC News reported.

  • Although the study identified significant differences between the blood samples of patients with long COVID and those without, further research will be needed to determine what biomarker thresholds are considered abnormal and possibly indicative of long COVID, per CNN.
  • Putrino noted that though the results show that long COVID is observable with blood testing protocols it also "varies from patient to patient depending on their specific medical history."

The big picture: Researchers compared the blood samples of people with long COVID symptoms at least four months after their infection, those who had fully recovered from a case of COVID, and those who'd never been infected with the virus.

  • They found that people with long COVID had irregular levels of different types of immune cells and that dormant viruses — like Epstein-Barr virus — had reactivated in long COVID patients.
  • Study participants with long COVID also had significantly lower-than-normal levels of the stress hormone cortisol, which helps give people a feeling of alertness.
  • "These findings show us that people with long COVID are living with a disease process that is observable," Putrino added in the press release.

State of play: A study of nearly 10,000 Americans earlier this year identified the most common symptoms seen in long COVID patients. They included fatigue, brain fog, dizziness and heart palpitations.

  • There's still no standard protocol for diagnosing or treating the myriad of symptoms that afflict some patients for weeks and months after they become infected with COVID.
  • However, in July the National Institutes of Health launched clinical trials for four possible long COVID treatments.

What to watch: "These markers need to be validated in larger studies, but provide a first step in dissecting the disease pathogenesis of long COVID," Akiko Iwasaki, another of the study's authors, said in the press release.

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