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COVID-19 May Reactivate Dormant Viruses Linked to Long COVID

Date: August 15, 2026
Source: Boston Children’s Hospital

COVID-19 may have effects that extend beyond the initial infection. New research suggests that the disease can trigger the reactivation of viruses that have remained inactive inside the body for years. Some of these viruses, including Epstein-Barr virus (EBV), cytomegalovirus (CMV), and herpesviruses, are widespread in the population and generally remain controlled without causing noticeable illness.

A newly reported study involving researchers from Boston Children’s Hospital and institutions throughout the United States has identified evidence that COVID-19 can stimulate the activity of several persistent viruses in hospitalized patients. The findings, published in Nature, could provide additional clues about how viral reactivation may contribute to prolonged illness and potentially long COVID.

A Large-Scale Search for Viral Reactivation

The investigation involved 1,154 hospitalized patients recruited through 20 biomedical research centers in the United States. Researchers analyzed extensive biological samples collected during the patients’ illnesses and examined genetic data for evidence that previously controlled viruses had become active again.

Ofer Levy, MD, PhD, director of the Precision Vaccines Program at Boston Children’s Hospital, participated in the NIH-supported project as a site principal investigator.

The research was designed to identify biological markers that could help explain differences in COVID-19 severity and subsequent health outcomes. Over the course of the project, scientists collected more than 200,000 samples and generated more than one billion data points, creating one of the largest datasets examining biomarkers associated with COVID-19.

Multiple Dormant Viruses Became Active

During the first 40 days following hospital admission, scientists detected evidence of reactivation involving 11 different viruses.

Among the viruses observed most frequently were Epstein-Barr virus, herpes simplex virus type 1, cytomegalovirus, and members of the Anelloviridae family.

Anelloviridae attracted particular attention because its reactivation showed a notable relationship with long-term physical disability and symptoms associated with long COVID.

Anelloviruses are poorly understood and are believed to persist in a large proportion of the population. Although their presence is extremely common, their effects on human health are still being investigated.

Researchers emphasize that the observed association does not by itself prove that Anelloviridae reactivation causes long COVID. However, the finding raises the possibility that these viruses could serve as biomarkers or could participate in biological processes associated with prolonged recovery.

Inflammation Could Be a Key Trigger

The study also produced an important observation concerning Epstein-Barr virus and cytomegalovirus.

Researchers found patterns suggesting that viral reactivation may be connected to inflammation rather than simply occurring because the immune system becomes severely weakened.

This is significant because viral reactivation has traditionally been associated with situations in which immune defenses are suppressed. The new findings suggest that intense systemic inflammation may itself contribute to previously controlled viruses becoming active again, even when patients do not appear to have a fundamentally impaired immune system.

Severe COVID-19 can produce substantial inflammatory activity throughout the body. According to the researchers, this inflammatory environment may create conditions that allow certain persistent viruses to resume replication or become detectable in the bloodstream.

Possible Connection With Long COVID

The relationship between Anelloviridae and long-term disability could provide another avenue for investigating why some people experience persistent symptoms after recovering from the initial coronavirus infection.

Long COVID can involve prolonged fatigue, reduced physical capacity, cognitive difficulties, and a range of other symptoms. Scientists are still working to understand why recovery is rapid for some individuals while others experience health problems for months or years.

The new findings suggest that interactions between SARS-CoV-2, the immune system, inflammation, and viruses that already reside in the body may be part of this complex picture.

Ofer Levy noted that identifying viral and molecular patterns associated with long COVID could eventually contribute to improved understanding, diagnostic approaches, and potential treatments.

Why the Findings Matter

The research highlights the importance of looking beyond SARS-CoV-2 itself when studying the consequences of COVID-19.

The human body contains numerous viruses that can persist for long periods after an initial infection. Under certain circumstances, changes in immune activity or inflammation may alter the balance between these viruses and their host.

Understanding when and why such viruses become active could help researchers determine whether viral reactivation is simply a consequence of severe illness or whether it contributes directly to longer-term complications.

The findings may also encourage researchers to explore whether monitoring specific viral markers could help identify patients at greater risk of prolonged recovery.

Looking Ahead

Although COVID-19 no longer dominates public attention as it did during the height of the pandemic, the virus continues to cause serious illness and long-term health consequences.

Researchers say the lessons learned from COVID-19 remain important, particularly because future coronavirus outbreaks or other respiratory pandemics are possible.

Further studies will be needed to determine whether the viruses identified in this research actively contribute to long COVID or merely reflect the inflammatory and immune changes associated with severe infection.

For now, the study adds an important piece to the long-COVID puzzle: the consequences of a coronavirus infection may involve not only SARS-CoV-2 itself, but also complex interactions with viruses that have been quietly present in the body for years.

Important note: The study demonstrates associations between COVID-19, viral reactivation, and later outcomes; it does not establish that dormant-virus reactivation is the direct cause of long COVID. More research is needed to determine whether these viruses are drivers, biomarkers, or byproducts of the disease process.