Much is still unknown about the novel coronavirus that has infected more than 137,000 people across the globe and killed more than 5,000. But as the United States and other countries have been confronting the increasing threat of COVID-19, many have asked whether it’s possible for patients to catch the coronavirus more than once.
In mainland China, where the outbreak originated and where the majority of cases occurred, there have been more than 100 reported cases of patients released from hospitals, who later tested positive for the coronavirus a second time, according to the Los Angeles Times.
In at least one instance, a 36-year-old man died earlier this month in Wuhan, China, the epicenter of the outbreak, five days after health officials declared he had recovered and discharged him from the hospital. In China’s Guangdong province, health officials said 14 percent of people who recovered in the province who were later retested were positive.
Similar cases have been reported in Japan and South Korea.
A woman working as a tour bus guide in Japan tested positive for coronavirus for the second time after developing a sore throat and chest pain. She first tested positive in late January and was discharged from the hospital in early February after showing signs of recovery.
“Once you have the infection, it could remain dormant with minimal symptoms,” Philip Tierno Jr., professor of microbiology and pathology at New York University, told Reuters last month.
“And then you can get an exacerbation if it finds its way into the lungs,” he said.
Scientists agree reinfection is an unlikely explanation for patients who test positive a second time, according to the Los Angeles Times, and note the possibility that testing errors, and releasing patients from hospitals too prematurely, are more likely the reason for reports of patients who retest positive.
“If you get an infection, your immune system is revved up against that virus,” Keiji Fukuda, director of Hong Kong University’s School of Public Health, told the Los Angeles Times. “To get reinfected again when you’re in that situation would be quite unusual unless your immune system was not functioning right.”
Fukuda told the paper that it’s more likely patients are being released from hospitals while carrying dormant fragments of the disease that are not infectious, but resemble the virus when tested.
“The test may be positive, but the infection is not there,” he said.
In a hearing before the House Oversight and Reform Committee on Thursday, Anthony Fauci, director of the National Institute of Allergy and Infectious Disease, was asked if people who have contracted the virus might now be immune.
“We haven’t formally proved it, but it is strongly likely that that’s the case,” Fauci said. “Because if this acts like any other virus, once you recover, you won’t get reinfected.”