Researchers at Yale School of Medicine say they have discovered there are some extra health impacts for people who suffer from long COVID.

In a pre-print study, researchers found patients suffering from long COVID symptoms tended to have exhausted T-cells and lower cortisol levels. They also found Epstein-Barr viral cells already present in those patients’ bodies had been reactivated.

Epstein-Barr is the virus that causes mononucleosis and is associated with multiple sclerosis.

"There's viruses like EBV and others that can cause chronic syndrome in a subset of people,” said Dr. Akiko Iwasaki, Yale School of Medicine. “And we're not saying that's what's happening in long COVID, but there may be a link between EBV and some of the symptoms that we are seeing - fatigue and post recessional malaise in these people."

An estimated 95% of adults carry dormant traces of Epstein-Barr Virus.