Study finds severe COVID-19 can reactivate dormant viruses, potentially explaining long COVID

A study published in Nature reveals that severe COVID-19 can reactivate dormant pathogens, such as Epstein-Barr, cytomegalovirus, and Anelloviridae, in nearly half of hospitalized patients. Led by the University of Texas at Austin, researchers analyzed over 1,100 patients and found that reactivation occurs even in immunocompetent individuals, driven by systemic inflammation. Notably, Anelloviridae reactivation strongly correlates with long COVID, while respiratory cytomegalovirus and nasal Epstein-Barr reactivations are linked to higher mortality rates within one year.

Severe COVID-19 viral reactivation

• ▪A study published in Nature on August 5, 2026, found that severe COVID-19 infections can reactivate dormant viruses already present in patients' bodies.
• ▪Viral reactivation occurred in patients with otherwise healthy immune systems, challenging the belief that it only happens in immunocompromised individuals.
• ▪Patients receiving immunosuppressive drugs were no more likely to experience viral reactivation than those who were not taking such medication.
• ▪The study found that nearly half of the hospitalized COVID-19 patients analyzed showed evidence of dormant viral reactivation during their illness.

Epstein-Barr virus reactivation

• ▪Severely ill COVID-19 patients with Epstein-Barr virus detected in their nasal cavity were more likely to die within one year.
• ▪Epstein-Barr virus RNA was detected early in COVID-19 infection, with 24% of patients having detectable levels near hospital admission followed by a gradual decline.

Cytomegalovirus reactivation patterns

• ▪The presence of cytomegalovirus in blood cells was linked to serious complications including bacteremia, kidney complications, stroke, and shock.
• ▪Severely ill COVID-19 patients with Epstein-Barr virus detected in their nasal cavity were more likely to die within one year.
• ▪Cytomegalovirus and herpes simplex virus became active around three weeks after hospital admission, primarily in the respiratory tract and lungs.

Long COVID potential causes

• ▪Reactivation of Anelloviridae, a virus family dormant in roughly 90% of people, was strongly associated with long COVID and long-term physical disability.
• ▪The study authors caution that the findings show only an association and do not prove that reactivated viruses directly cause long COVID.

IMPACC study methodology

• ▪The study measured the RNA of actively replicating viruses rather than relying on antibody responses to identify viral reactivation.
• ▪The observational study analyzed longitudinal data from 1,154 unvaccinated patients hospitalized with COVID-19 across 20 US hospitals from May 2020 to March 2021.
• ▪The study generated more than 1 billion data points from 200,000 nasal swabs, blood cells, and endotracheal aspirates generated during the IMPACC study.

CDC director confirmation

• ▪Erica Schwartz's confirmation as CDC director ended a nearly yearlong vacancy in the position after her predecessor was fired in August 2025.
• ▪The US Senate confirmed Erica Schwartz as the new director of the Centers for Disease Control and Prevention on August 5, 2026.