Severe COVID-19 infections can awaken dormant chronic viruses such as Epstein-Barr and anelloviruses, even in previously healthy individuals, according to a major study published in Nature. Researchers analyzing over 1,000 hospitalized patients discovered that these viral reactivations correlate with inflammation and long COVID symptoms.
Medical science long assumed that dormant viruses hiding quietly inside human tissue only reawakened when a patient’s immune system was severely compromised by conditions like immunosuppressive drugs. A multi-institutional study cns.utexas.edu has challenged that assumption, revealing that severe cases of COVID-19 can disrupt the body’s internal viral ecosystem.
Researchers tracking hospitalized patients discovered that an acute coronavirus infection acts as a profound physiological stressor. Rather than fighting a single pathogen, the body often faces a secondary wave of reawakened infections that are associated with systemic inflammation and complicated recovery.
Tracking a Billion Data Points Across 20 U.S. Hospitals
The findings stem from an observational analysis utilizing longitudinal data gathered through the Immunophenotyping Assessment in a COVID-19 Cohort (IMPACC) study. Between May 2020 and March 2021, investigators enrolled 1,154 unvaccinated patients hospitalized with COVID-19 across 20 hospitals in the United States.
The research consortium went far beyond measuring antibodies. By collecting more than 200,000 nasal swabs, blood cells, and endotracheal aspirates, the team generated over one billion data points. Scientists used bulk ribonucleic acid (RNA) sequencing to detect actively replicating viral transcripts rather than relying solely on past immune exposure.
Out of the cohort, 1,148 patients had sufficient data for viral analysis, and researchers found evidence of at least one reactivated virus in 550 of them, amounting to 47.9 percent of the group. Most of those individuals carried a single reactivated pathogen during their acute hospital stay.
Different Viruses Emerge on Separate Timelines
The study mapped out distinct temporal patterns for how hidden pathogens reawaken. Viruses do not flood the body all at once; instead, distinct families follow their own reactivation schedules during and after a severe coronavirus infection.
Epstein-Barr virus (EBV), which causes mononucleosis, typically surges early. Researchers detected EBV RNA in 24 percent of participants during the first eight days after hospital admission, followed by a gradual decline. Similarly, members of the Anelloviridae family remained steady in patient samples for roughly 20 days before slowly dropping off.
By contrast, other pathogens took longer to surface. Cytomegalovirus (CMV) and herpes simplex virus (HSV) generally reactivated later, peaking approximately three weeks after hospitalization and appearing predominantly in respiratory samples.
Anelloviruses and the Lingering Mystery of Long COVID
Among the most pressing discoveries was the link between specific viral signatures and post-acute sequelae, commonly known as long COVID. While about 80 to 90 percent of the population carries harmless Anelloviridae families latent in their bodies, the persistent detection of these viruses during convalescence told a different story.
Researchers identified an association between reactivated Anelloviridae and a long COVID phenotype marked by physical deficits, chronic fatigue, and reduced physical function. Investigators noted that this correlation persisted even after adjusting for age, initial disease severity, and medication-related immune suppression.
Elevated EBV and CMV levels in severely ill patients also tracked with a higher risk of death within one year.
Challenging Assumptions About Immune Suppression
The realization that viral reactivation happens frequently in immunocompetent people challenges long-held medical dogmas. Patients in the cohort who received immunosuppressive drugs during their hospital stay were no more likely to experience virus awakenings than those who took no such medication.
Instead of immune suppression driving the reawakenings, systemic inflammation and severe physiological stress appear to act as the primary triggers. Esther Melamed, principal investigator and assistant professor of neurology at Dell Medical School, noted that the coronavirus probably induces the stress that triggers the reactivations, which then amplify the body’s inflammatory response.
While the study stops short of proving that dormant viruses directly cause severe illness or long COVID, experts emphasize that existing antiviral medications and diagnostic tests for herpesviruses could eventually offer new pathways for patient care. Determining whether treating these awakened pathogens improves clinical outcomes remains the critical next step for researchers.
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