The immediate takeaway is not that COVID-19 has been proven to cause long COVID by reawakening other viruses. A 2026 study instead found a notable association: among people hospitalized with COVID-19, signs of active replication from normally dormant viruses appeared alongside severe illness and were linked with some worse later outcomes. That makes viral reactivation a research lead, not a diagnosis, a screening rule, or a treatment plan.
For people trying to understand persistent symptoms after COVID-19, the practical trade-off is between taking a plausible biological clue seriously and reading more certainty into it than the evidence supports. The study was large and detailed, but it was observational and focused on patients hospitalized during an earlier phase of the pandemic.
What the researchers examined
The University of Texas at Austin-led research used longitudinal data from 1,154 hospitalized patients enrolled in the Immunophenotyping Assessment in a COVID-19 Cohort, or IMPACC, study. Participants were treated at 20 U.S. hospitals between May 2020 and March 2021, and reports on the study describe them as unvaccinated.
This was not a trial in which researchers gave patients a treatment and measured the result. It was an observational analysis designed to track biological signals during and after serious COVID-19. Researchers analyzed more than 200,000 samples, including nasal swabs, blood cells and endotracheal aspirates, producing more than 1 billion data points.
A key feature was the use of viral RNA, which can signal active replication, rather than relying solely on antibodies that may reflect a past infection. Researchers reported RNA from 11 reactivated viruses within the first 40 days after hospital admission. The reported viruses included herpes simplex 1, Epstein-Barr virus, cytomegalovirus and Anelloviridae.
Why the associations matter for long COVID research
Many chronic viruses can remain in the body without causing obvious symptoms in people with healthy immune systems. Severe illness can alter immune function and create conditions in which such viruses become active again. The study found that viral reactivation was associated with COVID-19 severity, and it reported particularly strong links between Anelloviridae reactivation and long COVID and longer-term physical disability.
In a subset of severely ill patients, the analysis also associated cytomegalovirus in the respiratory tract and Epstein-Barr virus in the nasal cavity with a higher likelihood of death within one year. Those findings are clinically consequential because they point to biological patterns that may help researchers sort patients by risk in future studies.
But association is not a verdict on cause. A reactivated virus could contribute to a poor outcome, be a consequence of severe illness, or track another immune change that drives both. The available evidence does not separate those explanations.
What the study does not establish
The population is the central limitation. These were hospitalized patients, so the results should not be assumed to apply to everyone who has had COVID-19, including people with mild or asymptomatic infections. The data were also collected from May 2020 through March 2021, before vaccination was available to the participants described in the reports and before later variants changed the infection landscape.
The evidence also does not show that a person with lingering symptoms should presume Epstein-Barr virus, cytomegalovirus, or another dormant virus has reactivated. It does not validate routine testing for reactivation after COVID-19, and it does not show that treating a reactivated virus would prevent or resolve long COVID.
That distinction matters. Long COVID is not one uniform condition, and a signal found in a severely ill hospital cohort may represent one pathway among several rather than a universal explanation. The study’s value is in narrowing questions for follow-up research, not in settling them.
Known findings, remaining uncertainty, and sensible next steps
Known from this research
In this hospitalized cohort, researchers detected active RNA signals from multiple chronic viruses and found that reactivation patterns were associated with illness severity and selected longer-term outcomes. The study used repeated biological samples rather than a single snapshot, which strengthens its ability to describe when those signals appeared during hospitalization.
Still uncertain
Researchers have not yet shown whether preventing reactivation changes outcomes. They also have not established how frequently these findings occur in vaccinated people, in later COVID-19 waves, or in people who were never hospitalized. The reports do not provide an absolute risk figure that would let an individual estimate their own chance of long COVID or a later complication.
What patients and clinicians can take from it now
The study supports continued investigation of immune disruption and chronic-virus activity after severe COVID-19. It does not support self-diagnosis or a new medication decision based on these results alone. People with persistent or worsening symptoms after an infection should seek individualized clinical evaluation; this research cannot identify the cause of symptoms in any one person.
The next useful evidence will come from studies that repeat the RNA-based approach in contemporary, more diverse groups and test whether a specific intervention changes patient-centered outcomes. Until then, viral reactivation is best understood as an important hypothesis backed by a substantial observational dataset—not a proven explanation for every case of long COVID.
The useful shift in this story is from a broad claim about COVID-19 “awakening” viruses to a more specific question: what can an intensive hospital-based dataset reveal about later risk? The answer is meaningful but bounded. Researchers found active viral RNA signals and outcome associations in people with severe COVID-19, strengthening the case for studying immune disruption and chronic-virus activity together. Yet the design cannot determine direction of cause and effect, and the 2020-2021 unvaccinated cohort is not a stand-in for every current infection. The research may help shape future biomarker and intervention studies, but it does not change individual diagnosis or treatment today.
Sources and methodology
- UT-led study finds COVID-19 can awaken hidden viruses ... - https://dellmed.utexas.edu/news/ut-led-study-finds-covid-19-can-awaken-hidden-viruses-throughout-the-body
- Severe COVID may awaken dormant viruses, leading to ... - https://www.cidrap.umn.edu/covid-19/severe-covid-may-awaken-dormant-viruses-leading-autoimmune-disease-long-covid
- Study finds COVID-19 can reactivate dormant viruses - https://www.aha.org/news/headline/2026-08-07-study-finds-covid-19-can-reactivate-dormant-viruses
- Covid-19 Can Reawaken Dormant Viruses in the Body ... - https://www.smithsonianmag.com/smart-news/covid-19-can-reawaken-dormant-viruses-in-the-body-which-might-worsen-symptoms-of-the-respiratory-illness-study-suggests-180989322
