Infections on the rescue flight
Officials say a man in his 50s on board Wednesday's flight reported throat pain and later developed a fever before testing positive. Two other passengers, a man in his 40s and a woman in her 50s, showed no signs of infection but tested positive too.
The government arranged a second chartered flight to bring 210 people home. It arrived at Haneda Airport in Tokyo on Thursday, and 13 passengers were found to have fevers or other symptoms. They were taken straight to hospital.
Foreign ministry officials say about 300 people have asked to return to Japan from the city of Wuhan.
The government plans to secure more flights to bring them back.
Spreading in Japan
On Wednesday, health officials in Osaka confirmed that a tour guide in her 40s has been infected with the coronavirus. She was riding on a bus carrying tourists from Wuhan. The bus driver had earlier tested positive -- the first case of a Japanese person who had not been to Wuhan contracting the virus.
The number of confirmed cases in Japan now stands at 11.
Keep calm, take precautions
Experts are urging people not to panic, saying infections don't necessarily lead to pneumonia. The World Health Organization says only 20 percent of reported cases have been severe. The organization said last week that each infected person transmits the virus to between 1.4 and 2.5 people. Influenza has a transmission rate of between 2 and 3 people.
Health officials are advising people to take the same precautions as they would against the flu, such as washing hands regularly, using disinfectant and wearing masks.
Tracing the origin
In China, the Wuhan Institute of Virology of the Chinese Academy of Sciences said the new coronavirus may have come from bats. Their report says the gene sequence is 96 percent identical to that of a bat virus. Severe Acute Respiratory Syndrome, or SARS, also originated with bats, and was transmitted to humans via other wild animals.
Researchers at the Peter Doherty Institute for Infection and Immunity in Australia say they have managed to grow the new coronavirus.
They say the breakthrough will help researchers test vaccines and develop ways to detect infections before any symptoms appear.
Anthony Fauci at the US National Institute of Health announced on Tuesday that researchers have begun working with biotech firm Moderna to develop vaccines. He said they expect to start testing within three months.
The Baylor College of Medicine in Texas is cooperating with the New York Blood Center and China's Fudan University to develop a vaccine.
Professor Peter Hotez, a vaccine expert at Baylor, says the pace of development is increasing. But he also says it will take at least a year to confirm both effectiveness and safety.