It’s a viral blast from the past.
A new study suggests that COVID-19 can flip the switch on long-dormant viruses quietly hiding inside the bodies of people who were otherwise healthy before they fell ill.
Researchers at the University of Texas at Austin say the viral reawakening could help explain some of the mysteries behind long COVID, a debilitating chronic condition that affects millions around the globe.
The study followed more than SARS-CoV-2, the virus that causes the disease. None had received a coronavirus vaccine at the time.
The researchers grouped the patients based on how severely they were affected, from those who had mild cases and recovered quickly to those who died within 28 days of being admitted to the hospital.
The team collected samples throughout their hospital stays and for up to a year after discharge. The samples came from blood, nasal passages and, in patients who needed ventilators, fluid from breathing tubes.
After putting the samples through a battery of tests, the researchers found that nearly half of the patients had at least one dormant virus spring back to life during their COVID-19 illness.
The reawakened pathogens included Epstein-Barr virus, which causes mononucleosis, as well as other members of the herpes family. These viruses can lurk in the body for years before flaring up during times of stress or illness.
“This finding suggests that COVID-19 may not always act as a single viral infection and may disrupt the body’s internal ecosystem of dormant viruses,” Dr. Cole Maguire, the study’s lead author, said in a press release.
Even more surprising, the viral reawakening wasn’t limited to people with weakened immune systems. It frequently happened in patients who had been healthy before coming down with COVID-19.
Those whose dormant infections resurfaced were more likely to suffer severe illness, spend more time in the hospital, develop serious complications and die.
The researchers said the discovery could eventually change how doctors approach both acute COVID-19 and long COVID.
“Tests already exist for several of the chronic viruses studied, and some viruses in the herpes family can be treated with existing antiviral drugs,” said Dr. Esther Melamed, the study’s principal investigator.
“The next step is determining whether identifying and treating reactivated viruses can improve outcomes for patients with acute COVID-19 and long COVID.”
Long COVID remains one of the biggest unanswered questions of the pandemic. The condition can strike after a SARS-CoV-2 infection and leave patients battling a wide range of symptoms, including crushing fatigue, brain fog and physical disability.
Scientists still don’t fully understand what causes long COVID, and there are currently no approved treatments.
But its reach is enormous. A study published in May estimated that roughly one in six people infected with SARS-CoV-2 develop long COVID, with many going on to experience lasting health problems.
Worldwide, more than 400 million people are believed to have experienced the chronic condition at some point — contributing to an estimated $1 trillion annual global economic impact tied to lost work and medical costs.
The researchers stressed that their study doesn’t prove dormant viruses cause long COVID. However, they said their findings provide evidence that viral reactivation may play a role and could help scientists better understand — and eventually treat — the condition.
While the exact number of Americans who have been infected with SARS-CoV-2 remains unknown, a 2022 study found that more than half of the US population had contracted the virus during the first two years of the pandemic.
Today, experts consider COVID-19 endemic in the US, meaning the virus continues to circulate at predictable levels rather than causing the massive waves seen early in the pandemic.
As of Aug. 5, the CDC estimates that COVID-19 infections are increasing or likely increasing in 43 states, though the percentage of emergency room visits tied to the virus is “very low.”
