Omicron amps up concerns about long COVID and its causes

More than a year after a bout with COVID-19, Rebekah Hogan still suffers from severe brain fog, pain and fatigue that leave her unable to do her nursing job or handle household activities.

More than a third of COVID-19 survivors by some estimates will develop such lingering problems. Now, with omicron sweeping across the globe, scientists are racing to pinpoint the cause of the bedeviling condition and find treatments before a potential explosion in long COVID cases.

Momentum is building around a few key theories.

One is that the infection or remnants of the virus persist past the initial illness, triggering inflammation that leads to long COVID.

Another is that latent viruses in the body, such as the Epstein-Barr virus that causes mononucleosis, are reactivated. A recent study in the journal Cell pointed to Epstein-Barr in the blood as one of four possible risk factors, which also include pre-existing Type 2 diabetes and the levels of coronavirus RNA and certain antibodies in the blood. Those findings must be confirmed with more research.

A third theory is that autoimmune responses develop after acute COVID-19.