Nearly 100 people in South Korea have tested positive for the coronavirus after initially being cleared, sparking concerns for the growing possibility of double cases.
The number of relapsed cases grew from 51 on Monday and officials are unsure what has sparked the trend. Epidemiological investigations are under way.
The potential for individuals to be reinfected with Covid-19 is of grave concern for health officials, who anticipated infected populations would develop sufficient immunity to protect against a further spread of the pandemic.
However Jeong Eun-kyeong, the director of the Korea Centres for Disease Control and Prevention, said the virus could have been "reactivated", as opposed to patients being reinfected a second time.
Kim Woo-joo, a professor of infectious diseases at the Korea University Guro Hospital, said patients could have "relapsed", while other experts said false test results could be to blame.
"There are different interpretations and many variables," Jung Ki-suck, a professor of pulmonary medicine at the Hallym University Sacred Heart Hospital said.
But the clinical chair of Infection Prevention and Disease Control at the University of Sydney, Ramon Shaban, did not rule out the possibility of double cases, adding it was currently unclear whether or not the antibodies victims produce from the virus were strong enough to prevent getting it again.
"We know individuals who have Covid-19 do develop antibodies but what we don't know is the extent to which those antibodies provide a strong protective effect," he told the ABC this morning.
"We know that ordinarily, with the infections, we produce antibodies but they tend to wane after a period of time.
"With influenza, we develop an immune response but that wanes after weeks and months. We are trying to understand to what extent do our antibodies protect us? If so, for how long?
"We have been looking for this kind of data to understand do the antibodies last for quite some time? If so, to what extent do they protect us from future infection, more broadly."
More than 1,650,000 cases of coronavirus have now been confirmed across 185 countries, according to the latest figures from Johns Hopkins University.
The global death toll has now passed 100,000 and about 366,000 people have recovered.
The highest numbers of cases remain in the United States (475,000+), Spain (157,000+), Italy (147,000+), Germany (119,000+) and France (118,000+).
The highest death tolls have been reported in Italy, Spain, France, the United Kingdom and New York City.