Iron Disappears After COVID: Scientists Identify Possible Cause of Long-Term Fatigue

Disrupted iron metabolism following SARS-CoV-2 infection may play a key role in the development of long COVID. Researchers have found that, in some patients, persistent iron redistribution begins early in the infection and can continue for months after recovery.

Scientists analyzed blood samples from people who had recovered from COVID-19, following them over an extended period. The study revealed that in patients who later developed long COVID symptoms, signs of impaired iron regulation and ongoing inflammation appeared just a few weeks after infection. These changes occurred regardless of age, sex, or the severity of the initial illness.

The results were published in Nature Immunology.

During infection, the body activates a defense mechanism: iron levels in the blood drop because many microorganisms use iron for growth. To limit their proliferation, the body temporarily “hides” iron. However, researchers discovered that in some individuals after COVID, this mechanism continues to function for too long. Iron does not leave the body, but it accumulates inside immune cells and tissues, becoming unavailable to the bloodstream.

This hidden redistribution of iron can create a state resembling functional deficiency. Even though iron is present in the body, there is insufficient availability for normal red blood cell production and efficient oxygen transport. As a result, cells receive less energy, which may lead to characteristic long COVID symptoms—chronic fatigue, weakness, and reduced exercise tolerance.

According to the researchers, understanding these processes could help develop new treatment strategies. In particular, early control of inflammation and restoration of normal iron distribution may be promising approaches. They emphasize that simply prescribing iron supplements is not always effective, as the problem lies not in the amount of iron but in its being “trapped” inside cells.

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