Scientists have proposed a number of explanations for long Covid with two leading theories: that symptoms are driven by the immune system or by the persistence of the virus in the body.
The immune theory suggests that Covid-19 turns the immune system against the body. This could explain symptoms like racing heart, dizziness, weakness, and micro clots in the blood.
The second theory is that the virus can remain in the body and brain long after acute infection, and its genetic material can persist up to 230 days after symptoms arise according to a recent National Institutes of Health preprint.
Lingering virus is often found not in the blood but rather in a person’s tissues.
In long Covid, viral reservoirs could continue to injure tissues directly.
They may leak viral proteins into the bloodstream, where they can spur the formation of the micro clots and activate the immune system, leading to inflammation and further damage.