Experts from the World Health Organization on Monday said it is unclear whether recovered COVID-19 patients will have immunity from being infected by the virus for a second time.
Questions arose late last week after 51 patients in South Korea tested positive for the virus after recovering from COVID-19.
The general thinking among experts has been that those who become infected will have immunity from becoming reinfected, but that is based on how viruses behave in general. Studies have not been able to conclusively determine whether a second infection is possible with COVID-19.
“We do not have the answers to that; that is an unknown,” said Dr. Michael Ryan, executive director of WHO’s emergencies program. “One would expect that a person who generates a full-blown immune response with detectable antibodies should have protection for a period of time. We just don’t know what that period of time is.
“We would expect that to be a reasonable amount of time, but it is very difficult to say with a new virus, and we can only extrapolate from other coronaviruses, and even that data is quite limited.”
Dr. Maria Van Kerkhove, who has led WHO’s research into coronavirus, said that a study in Shanghai examined 175 recovered patients. While some recovered patients showed a strong antibody response, others showed no antibody response, she said.
The study has not been peer reviewed, Van Kerkhove said. A number of other studies are underway, but with a new virus, the information is limited, Van Kerkhove added.
“Right now, the information is mixed,” she said. “We need much more information from recovered patients.”
Last week, Korea’s Centers for Disease Control said there were 51 “re-confirmed cases” of COVID-19 in the country. Korea’s CDC said it is investigating to see if these patients became reinfected with the virus.