Authorities, experts look into Korea’s first coronavirus ‘reinfection’ case

Yonhap via The Korea Herald/Asia News Network

SEOUL — A Korean woman who had been discharged after recovering from the novel coronavirus has tested positive for the disease again, in the country’s first such case, fueling questions over the possibility of reinfection.

A further epidemiological study is required to determine what exactly happened, but local authorities have played down the possibility that it could be a case of reinfection from someone else.

Rather, the virus might have been dormant in the patient, and the illness reappeared in the patient because she was old and had a weak immune system.

“A normal person would have been able to defend from the virus invading the system again after developing immunity (against the coronavirus), but it could have been difficult (for her to do this),” Kwon Joon-wook, director of the National Institute of Health, said at a briefing Saturday. “So some experts say the virus might have not been completely dead (in the patient’s system).”

The 73-year-old woman, who lives in Siheung, Gyeonggi Province, was discharged from the hospital on Feb. 22 as she developed no further symptoms and tested negative twice successively in a 24-hour interval. She then had mild symptoms again and reported them to the community health center. She tested positive again for the virus on Friday afternoon.

It marks the first such case in Korea, where a total of 3,526 coronavirus cases and 17 deaths were reported as of Sunday morning.

Experts say it is likely that the virus had subsided with treatment and reactivated again afterwards. It is also possible the diagnostic test had been erroneous.

“Reinfection and recurrence (of COVID-19) are different,” said Eom Jung-sik, a professor of infectious disease at Gachon University Gil Hospital.

“I presume the patient still had low levels of the virus when she was discharged from the hospital, testing failed to pick it up and the virus recurred because of her weak immune system.”

If such cases continue to occur, there should be quarantine rules for recovered patients, such as keeping them in self-quarantine at their homes for a certain period of time after being released from hospitals and having them tested for the virus again, another expert suggested.

“The virus in the patient might have not been perfectly dead in her system, only partially,” said Kim Woo-joo, a professor of infectious medicine at Korea University Guro Hospital.

“Putting aside whether patients, who were discharged after a recovery and tested positive again, could infect others again, it is time to discuss what the government would do about recovered patients,” he said, citing a growing number of patients being discharged in the country.

As of Sunday morning, 30 people had been released from hospitalization after making a full recovery.

The government said it is to consult with the country’s clinical committee to look into this and other similar cases around the world in order to draw extra quarantine measures.

Similar cases have also been reported in China and Japan.

Japanese authorities on Wednesday confirmed that a woman who works as a tour bus guide had tested positive for COVID-19 for a second time, three weeks after she was discharged from the hospital upon showing signs of recovery.

As much remains unknown about the virus, there needs to be more research and data accumulated to determine the possibility of reinfection of the coronavirus.

“We need more research and study on how antibodies are formed after being infected with the virus, given the COVID-19 is a new virus,” Korea Centers for Disease Control and Prevention Director Jung Eun-kyung said at a briefing Thursday.

She also said that the accuracy of the diagnostic test, when and how the test was conducted and the severity of the patient’s symptoms need to be reviewed.