Severe COVID-19 reactivates dormant viruses, study finds
· Medical Xpressedited by Gaby Clark, reviewed by Robert Egan
Gaby Clark
Scientific Editor
Meet our editorial team
Behind our editorial process
Robert Egan
Senior Editor
Meet our editorial team
Behind our editorial process Editors' notes
This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility:
fact-checked
peer-reviewed publication
trusted source
proofread
The GIST Add as preferred source
Chronically infecting viruses—such as Epstein-Barr virus, cytomegalovirus (CMV) and herpesviruses—are common and often innocuous and asymptomatic. However, emerging evidence suggests their reactivation may contribute to autoimmune disease and other chronic conditions. In a new Nature study involving 15 biomedical research institutions across the United States, Boston Children's Hospital researchers and their collaborators discovered that COVID-19 reactivates certain dormant viruses in hospitalized patients. These findings expand understanding of chronically infecting viruses and could inform the development of strategies to combat their reactivation.
Physician-scientist Ofer Levy, MD, Ph.D., director of the Precision Vaccines Program (PVP) at Boston Children's, served as a site principal investigator for this study of 1,154 patients across 20 U.S. biomedical research hospitals designed to define biomarkers of COVID severity and outcomes. The research team used genomic sequencing to look for reactivated viruses in the patients because long-cleared viral infections can sometimes reawaken in times of stress.
"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," says Joann Diray Arce, Ph.D., who leads the PVP-Data Management and Analysis Core and is the lead of the study's Clinical and Data Coordinating Center.
Reactivations tied to later illness
The research team detected 11 reactivated viruses in patients within the first 40 days after admission. The most commonly detected were Epstein-Barr virus, herpes simplex virus 1, cytomegalovirus and Anelloviridae viruses. Notably, reactivation of Anelloviridae, a poorly understood family of viruses typically latent in about 90% of the population, was associated with long-term physical disability and long COVID.
"This association with long COVID is an interesting finding as millions around the world suffer from this chronic condition," says Levy. "Having new insight into the molecular and viral associations with long COVID could point the way to better understanding and ultimately better diagnostics and treatments."
Inflammation, not immune suppression
In an analysis of blood samples from the patients, Epstein-Barr virus 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 prevailing 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.
"Although many no longer think of COVID as a problem, 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," says Levy. "We need to help these patients recover with the best outcomes. Moreover, 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."
Next steps for this work will be to uncover how the immune system responds to these viruses over the course of COVID-19, with the aim of identifying effective therapeutics and establishing the optimal timing of any interventions.
Other Boston Children's researchers on the study include Jing Chen, Ph.D., Annmarie Hoch, Al Ozonoff, Ph.D., Kinga Smolen, Ph.D., and Hanno Steen, Ph.D.
Publication details
Esther Melamed, Virus reactivation in acute and long COVID-19, Nature (2026). DOI: 10.1038/s41586-026-10740-z. www.nature.com/articles/s41586-026-10740-z
Journal information: Nature
Key medical concepts
COVID-19 (Coronavirus Disease 2019)Herpesvirus 4, HumanCytomegalovirusPost-Acute COVID-19 SyndromeInflammation
Clinical categories
Infectious diseasesCommon illnesses & Prevention Provided by Children's Hospital Boston Who's behind this story?
Gaby Clark
MA in English, copy editor since 2021 with experience in higher education and health content. Dedicated to trustworthy science news. Full profile →
Robert Egan
Bachelor's in mathematical biology, Master's in creative writing. Well-traveled with unique perspectives on science and language. Full profile →
Citation: Severe COVID-19 reactivates dormant viruses, study finds (2026, August 5) retrieved 6 August 2026 from https://medicalxpress.com/news/2026-08-severe-covid-reactivates-dormant-viruses.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.