Two people in China who recovered from the novel coronavirus a few months ago have since tested positive for COVID-19 again, highlighting concerns over the possibility of reinfection.
A 68-year-old woman in Hubei, China, tested positive Sunday, six months after she was diagnosed with the novel coronavirus and recovered. Additionally, a man in Shanghai who was positive for the virus in April tested positive again on Monday, though he reportedly hasn’t shown any symptoms, according to a report from Bloomberg.
Those in close contact with the patients have not tested positive, though they have been quarantined, local authorities said, per Bloomberg.
The two cases raise the question about reinfection and immunity regarding the novel coronavirus. According to the Johns Hopkins School of Public Health website, the possibility of reinfection is low. Researchers are currently trying to understand how to measure a person’s immunity against the virus using antibody tests.
A recent study published by the Korea Centers for Disease Control and Prevention found patients who recovered from novel coronavirus and tested positive again weren’t infectious. The researchers stated in a news release that the viral material collected in the test was found to be dead virus. The study also found that most patients who recovered had neutralizing antibodies that may protect a person from getting sick again.
The researchers in the Korea study tested 790 people who were in close contact with the patients who tested positive again for the virus. The researchers said 27 tested positive, though none of the cases appeared to be caused by exposure to someone who was reinfected.
Meanwhile, other studies show the antibodies present in an infected person quickly drop after a few months, possibly indicating they could be susceptible to the same virus a second time.
However, another recent study showed that so-called “T-cells” have the possibility to provide immunity after the patient’s recovery from the virus.
“If they simply tested positive, I would do a culture to determine if this is just residual RNA or an actual second infection," to rule out if a person has an active case, Dr. Gary Simon, director of the Division of Infectious Disease at the George Washington University School of Medicine and Health Sciences, told Fox News in an email.
Dr. Glatt Aaron E. Glatt, an infectious disease specialist in New York, called the report of the two patients in China testing positive once more unusual.
"To date, according to the official [Centers for Disease Control and Prevention (CDC)] website, there has not been a proven case of COVID-19 occurring for [the] second time in a patient. There have been anecdotal reports of such occurring, but the documentation in such previous cases was lacking," Glatt, also a fellow for the Infectious Diseases Society of America, told Fox News. "These two cases, if real, would represent an important new finding, albeit still thankfully a very rare event."
“If reinfection is suspected, repeat isolation and contact tracing may be needed. The determination of whether a patient with a subsequently positive test is contagious to others should be made on a case-by-case basis, in consultation with infectious diseases specialists and public health authorities, after review of available information," according to the CDC.