Patients who were thought to have recovered from coronavirus in South Korea have reportedly tested positive again.
Officials said at least 116 people who were initially cleared of the infection have tested positive for Covid-19 days later.
Jeong Eun-kyeong, director of the Korea Centres for Disease Control and Prevention (KCDC), told a press briefing the virus may have been reactivated as opposed to the patients being re-infected.
He said: “While we are putting more weight on reactivation as the possible cause, we are conducting a comprehensive study on this.
“There have been many cases when a patient during treatment will test negative one day and positive another.”
Other experts said faulty tests may be playing a role, or remnants of the virus may still be in patients’ systems but not be infectious or of danger to the host or others.
Guidelines from the WHO state that before being discharged from hospital, a clinically recovered Covid-19 patient should test negative for the virus twice – with tests carried out at least 24 hours apart.
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The Covid-19 patients in South Korea were being considered for discharge after testing negative for the disease – however, tests administered later showed positive results.
Growing trend
Last week, the number of patients who were believed to have tested positive for a second time was 51 – but this jumped to 91 on Friday.
Soon after, the WHO announced it would begin looking into the trend.
The agency said in a statement: “We are closely liaising with our clinical experts and working hard to get more information on those individual cases. It is important to make sure that when samples are collected for testing on suspected patients, procedures are followed properly.”
According to WHO, current studies show that patients with mild Covid-19 experience a period of about two weeks between the onset of symptoms and clinical recovery.
But it remains unclear why these patients are testing positive after they were believed to have recovered.
The statement added: “As Covid-19 is a new disease, we need more epidemiological data to draw any conclusions.”
