Coronavirus can ‘reactivate’ in recovered patients, experts say. What does that mean?

Brooke Wolford

People who were thought to have recovered from the coronavirus tested positive again, indicating that patients can relapse, South Korean officials say.

South Korea reported nearly 7,000 COVID-19 recoveries, but after 91 patients re-tested positive, officials are worried it’s just the tip of the iceberg, and far more people will likely relapse as well, Reuters reported. China also found more than 100 people, who were thought to have recovered, tested positive for the virus a second time, revealing what could be a sinister global trend, McClatchy reported.

“The number will only increase, 91 is just the beginning now,” Kim Woo-Joo, professor of infectious diseases at Korea University Guro Hospital, told Reuters.

Officials say that the virus likely “reactivated” in coronavirus patients, rather than re-infecting them, Bloomberg reported. A confirmed case of coronavirus is considered to be recovered after the patient tests negative for COVID-19 twice within 24 hours, according to Bloomberg.

“While we are putting more weight on reactivation as the possible cause, we are conducting a comprehensive study on this,” Jeong Eun-kyeong, director-general of the Korean Centers for Disease Control and Prevention, told Bloomberg. “There have been many cases when a patient during treatment will test negative one day and positive another.”

Although the trend was also found in China back in mid-March, scientists believed that the second time patients tested positive for the virus was due to errors in testing and not reinfection, McClatchy reported.

“If you get an infection, your immune system is revved up against that virus,” Dr. Keiji Fukuda, director of Hong Kong University’s School of Public Health, told the Los Angeles Times. “To get re-infected again when you’re in that situation would be quite unusual unless your immune system was not functioning right.”

That’s why South Korean officials believe it’s about reactivation, not reinfection, according to Reuters. But they also theorized that false test results could be to blame “or remnants of the virus could still be in patients’ systems but not be infectious or of danger to the host or others,” Reuters reported.

Still, the possibility of coronavirus patients relapsing is of international concern, since many countries hope previously infected patients will develop immunity, Reuters said.