Can a blood test help diagnose long-COVID?

There is some good news: long-COVID prevalence among Americans has declined from 11% to 7.5% of those who have had COVID. Long-COVID symptoms are similar to those seen in autoimmune diseases — such as fatigue and brain fog. A new study shows there are differences in the blood of those who experience post-COVID symptoms and those who have recovered.

Researchers compared the blood samples of 268 people: those who had fully recovered from COVID, those who were never infected, and those who continued to experience symptoms at least four months after their long-COVID infection. The researchers found significantly lower cortisol levels and unusual activity in Long-COVID patients' T cells and B cells.

Cortisol is a naturally occurring hormone that can make individuals feel alert and awake. Low levels of cortisol would help explain long-COVID patients’ extreme fatigue. The study also found that dormant viruses, such as Epstein-Barr (which causes mono), are reactivated in patients with long-COVID. However, researchers did not find significantly elevated levels of antibodies in long-COVID patients versus those without. 

One hypothesis is that the COVID virus may still be lurking in areas such as the brain or other organs, leading to continued immune irregularity. Additional research is needed to fully understand the causes of these blood irregularities and low cortisol levels.

The Autoimmune Registry recently partnered with Open Medicine Foundation (OMF), which funds open, collaborative research to discover treatments and a cure for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS), Long COVID, and related chronic, complex diseases. Join OMF's StudyME Registry for access to critical ME/CFS and Long COVID research studies taking place worldwide. To learn more, please visit https://www.omf.ngo/.

To support the Autoimmune Registry, please join our registry or share it with a friend who has an autoimmune condition. Donations are also greatly appreciated!