Fear of reinfection grows after 124 people test positive for second time
South Korea has identified a growing number of people who make an apparent recovery from the coronavirus only to test positive again, raising fears that the virus is capable of striking the same person more than once.
The Korea Centres for Disease Control and Prevention (KCDC) reported 124 ‘‘relapsed’’ cases of Covid-19 yesterday, an increase of eight from the day before. Doctors are urgently investigating whether mutations in the virus can prevent patients from acquiring an immunity. ‘‘The virus will be divided and incubated, and genes will of course be analysed,’’ the deputy director of the KCDC, Kwon Jun-wook, said. ‘‘We are closely looking into possible genetic changes.’’
Among the 460,000 people around the world thought to have recovered from the virus so far, the number of relapsed patients in South Korea is small, and doctors warn that in the absence of systematic research it is too early to jump to conclusions.
Most experts and health authorities are working on the assumption that those who have got over the virus will acquire a degree of immunity to it which will over time reduce contagion. But the relapses in South Korea underline how much remains unknown about the disease.
Asked whether she feared a second wave of the virus, Kang Kyung-wha, South Korea’s foreign minister, acknowledged that ‘‘[of] those fully cured and released, many of them have been found to test positive a few days after’’.
She emphasised that the reason for patients testing positive for the virus twice was still not fully known. One explanation could be faulty testing. The relapsed patients may have been found positive when in fact they had not yet been infected by the virus, or alternatively the second test may have been a false positive.
South Korea has been praised for its programme of mass testing. But the larger the number of tests, the greater the chance of misleading results.
Standard tests used to detect the virus rely on identifying certain fragments of its genetic material. False negatives can result from swabs not gathering enough material from a person’s nose or throat. Meanwhile, a later false positive test may have picked up residual ‘‘fragments’’ of the virus that lingered in the patient’s nose and throat, but which were not capable of making that person sick or capable of infecting others.