COVID-19 has been found to reactivate certain chronic viruses that have been dormant in the body.
Researchers at Boston Children’s Hospital say there is emerging evidence that this reactivation may contribute to autoimmune disease and other chronic conditions.
One of the reactivated viruses was also strongly linked to long COVID – a condition where COVID-related symptoms continue for months or longer.
The viruses include Epstein Barr, cytomegalovirus (CMV), and herpes, which are “are common, and often innocuous and asymptomatic without reactivation”.
The study, published in the Nature journal this month, involved 15 biomedical research institutions across the United States.
The virus reactivation was found in hospitalised patients with COVID-19. The team found 11 reactivated viruses in patients within the first 40 days of admission.
“Notably (they found) reactivation of Anelloviridae, a poorly understood family of viruses typically latent in about 90 percent of the population, was associated prominently with long-term physical disability and long COVID,” the study report said.
Physician scientist Ofer Levy said the study involved 1154 patients and was designed to define biomarkers of COVID severity and outcomes.
They were seeking to explore the notion that “long-cleared” viral infections can sometimes reawaken in times of stress.
“This association with long COVID is an interesting finding as millions around the world suffer from this chronic condition,” Dr Levy said.
“Having new insight as to the molecular and viral associations with long COVID could point the way to better understanding and ultimately better diagnostics and treatments.”
Dr Levy said that, although many people no longer thought of COVID as a problem, up to 50,000 Americans died of COVID in 2025-2026 and up to 10 million US adults might suffer from long COVID.
“We need to help these patients recover with the best outcomes,” he said.
“Sooner or later, there may be another coronavirus pandemic, which means we need to learn all the lessons we can from COVID-19 to be better prepared.”
In the study, Epstein-Barr and cytomegalovirus seemed to activate in response to inflammation rather than immune system suppression.
The researchers say this is a surprising new mechanism, challenging the view that chronic viral reactivation is primarily a consequence of immunosuppression.
“This finding demonstrates that reactivations occur frequently in apparently immunocompetent individuals during severe illness and in association with increased systemic inflammation,” the study said.
The full report can be found here
