October 17, 2023

Biomarkers in the Blood Could Lead to a Long COVID Test

Research conducted at the Icahn School of Medicine at Mount Sinai and Yale School of Medicine was published in Nature, indicating the potential for a blood test to determine if an individual has long COVID.

Between January 2021 and June 2022, researchers studied blood samples from 273 individuals across three different sites, recruiting individuals that:

  • Had never been infected with COVID
  • Had fully recovered from COVID infection
  • Still showed symptoms at least four months after infection

Patients were asked to complete detailed questionnaires about their symptoms, along with medical history, and other health information.

Researchers identified biomarker differences and similarities between the groups, and then applied machine learning analyses to better understand which biomarkers were most effective in allowing the algorithm to identify patients with long COVID.

Upon establishing which biomarkers were most effective, researchers were able to differentiate between people with and without long COVID with 96% accuracy based on distinctive features in the blood samples.

Long COVID patients were found to have clear differences in immune and hormone function from patients without the condition. Individuals with long COVID had abnormal T cell activity, low cortisol levels, and reactivation of multiple latent viruses, including the Epstein-Barr virus and other herpesviruses.

These findings have made this the first study to show specific blood biomarkers that can accurately identify patients with long COVID, which researchers see as an important step in the development of blood testing protocols for long COVID that would help guide more personalized treatment of these patients.

Patients with long COVID frequently report unremitting fatigue, post-exertional malaise, and a variety of cognitive and autonomic dysfunctions. According to a recent WCRI study, the most common conditions listed on medical bills across long COVID claims included:

  • Lung conditions, which affected 64% of long COVID claimants
  • Heart conditions, which affected a third of long COVID claimants
  • Mental health conditions, which affected 12% of long COVID claimants

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