The coronavirus outbreak has reached a "decisive point" and has "pandemic potential", World Health Organization head Dr Tedros Ghebreyesus says.
Chinese health officials say that about 14% of people who had the coronavirus but recovered and were discharged from hospital have tested positive for the virus again. Health officials admit they're still learning about the new coronavirus and how it operates within the human body.
The same phenomenon has been reported in Japan, when a woman in her 40s who had recovered and tested negative for the virus then tested positive more than three weeks later. The authorities in both countries have pledged to continue tracking former patients, even after they've been discharged from hospital.