Severe COVID-19 reactivates 11 dormant viruses, study finds

A large multi-omic study of 1,154 hospitalised COVID-19 patients found that severe SARS-CoV-2 infection can reactivate 11 dormant viruses, including Epstein-Barr (EBV), herpes simplex 1 and cytomegalovirus. Reactivation was most detected within 40 days of admission and linked to disease severity.

Earlier research had already shown higher EBV reactivation in COVID-19 patients. A 2025 study reported EBV reactivation in 28.6% of people with persistent post-COVID symptoms, compared with 11.3% of controls. The authors said EBV reactivation 'plays a role' in Long COVID, though the observational design cannot establish causation.

Not all COVID patients experience reactivation; a separate study of mild cases found no EBV DNA in symptomatic individuals. Scientists caution that the phenomenon is not automatically dangerous and that its clinical significance requires further investigation.