COVID-19 Reactivates Dormant Viruses, Study Finds

Research conducted by Boston Children’s Hospital and affiliated institutions has uncovered that COVID-19 can reactivate dormant viruses in hospitalized patients. This significant discovery is detailed in a recent study published in Nature, which involved 15 biomedical research institutions across the United States.

The study monitored 1,154 patients across 20 U.S. biomedical research hospitals to identify biomarkers linked with the severity of COVID-19 and patient outcomes. Utilizing genomic sequencing, researchers sought evidence of dormant viruses reactivating during the stress of illness, with the aim of providing insights that could help craft strategies for managing these viral reactivations.

According to Dr. Ofer Levy, a physician scientist and director of the Precision Vaccines Program at Boston Children’s, who served as a principal investigator for this National Institutes of Health (NIH) funded research, “This is the largest and most comprehensive biomarker study of COVID-19, in which we followed more than one thousand patients, collected more than 200,000 samples, and generated more than 1 billion data points over the course of a year for this public resource.”

Dormant Viruses Reactivated

In the first 40 days following hospital admission, researchers detected 11 reactivated viruses, including Epstein-Barr, herpes simplex 1, cytomegalovirus, and Anelloviridae. Notably, the reactivation of Anelloviridae—a family of viruses that remains latent in approximately 90% of the population—was significantly associated with long COVID and long-term physical disability.

Dr. Levy noted, “This association with long COVID is an interesting finding as millions around the world suffer from this chronic condition. 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.”

Inflammation Linked to Viral Reactivation

Analysis of blood samples revealed an unexpected trend involving Epstein-Barr and cytomegalovirus. Instead of reactivating due to immune suppression, these viruses appeared to activate as a response to inflammation. This finding challenges the prevailing understanding that chronic viral reactivation is primarily linked to weakened immune systems.

Dr. Levy emphasized the ongoing impact of COVID-19, citing that, “up to 50,000 Americans died of COVID in the 2025-2026 respiratory season and some estimates suggest over 10 million U.S. adults suffer from long COVID.” He added the importance of continuing research to assist affected patients and prepare for potential future pandemics.

Future Research Directions

The research team plans to further explore how the immune system interacts with these reactivated viruses over the course of COVID-19, aiming to identify effective treatment protocols and optimal intervention timings. Other researchers involved in the study include Jing Chen, Annmarie Hoch, Al Ozonoff, Kinga Smolen, and Hanno Steen.