The strange neurological symptoms of "long-COVID" may have an explanation: another virus. A study has examined whether COVID promotes the reactivation of the Epstein-Barr Virus, an ubiquitous herpes virus that causes mono in teens. The evidence suggests that this is, indeed, the case, and it's EBV that's causing some of the long-COVID symptoms.
Epstein Barr virus
The Epstein-Barr virus has always been a bit mysterious. It is responsible for mononucleosis, and is suspected of being a cause of chronic fatigue syndrome, although this disease remains poorly understood. The concept of viruses causing cancer is not new.