A Japanese woman has become the first person in the world to catch coronavirus twice.
The tour-bus guide from Osaka has become infected by the Covid-19 strain of the disease for a second time.
Her falling ill confirms fears expressed by scientists that immunity caused by the disease could be relatively short lived.
The woman’s second positive test came as the number of confirmed cases in Japan rose by 16 to 186, in addition to the 704 diagnosed from the Diamond Princess cruise ship.
Dr Babak Ashrafi explained how it has been difficult to predict how the relatively new strain would act over time.
"Experts are busy gathering information from those who have become infected to see how well their immune systems react and how long they’ll remain immune," he told MetroOnline.
"We do know that when you catch a virus, your body learns how to fight it off.
"However, like our minds, our bodies can forget over time how to do this and immunity can wear off over time after initial infection."
The fact people can get the disease twice in a fairly short period of times heightens the potential impact of the disease.
Already significantly more than 80,000 people across the globe have coronavirus.
The relatively slow spread of the virus in Europe at the beginning of February has now sped up significantly.
Hundreds of people are infected in Italy where multiple people have died.
Countries including Austria, Switzerland and Croatia have all reported their first cases this week.
Two more patients in England have tested positive for coronavirus, bringing the total number of UK cases to 15.
One caught the killer bug during a trip to Italy and the other person had visited the Spanish island of Tenerife, where about 160 Britons are in a quarantine.
If the virus continues to spread as it has been for the past month then the viability of sporting events scheduled for this summer will be questioned.
Yesterday a spokesman for the Japanese government said the International Olympic Committee and local organizers are going ahead as planned with the Tokyo Olympics despite the threat of the spreading coronavirus.
The Olympics are set to open on July 24 with 11,000 athletes competing.
The Paralympics opens a month later and will see 4,400 compete.
There is some doubt about how Euro 2020 will function, with the tournament scheduled to be played across 12 European venues.
"We are at the waiting stage. We are monitoring country by country, and football must follow the orders of the individual countries," Italian Michele Uva, a member of the Uefa executive committee, told state broadcaster Rai.
"The sporting path will only be closed if the situation gets worse."