The previously unknown virus has caused global concern because of its similarity to the SARS pathogen, which killed hundreds across mainland China and Hong Kong in 2002-2003. Originating in Wuhan, Hubei’s capital, the virus has spread throughout China and around the world — with cases confirmed in Taiwan and about a dozen countries as far as the US. The flight is schedueld for tomorrow, it said in an e-mail to Americans in China that warned of “extremely limited” capacity for private citizens. Japan is coordinating with the Chinese government to swiftly evacuate its citizens, Japanese Prime Minister Shinzo Abe said. Health officials said the virus has since become transmissible between humans.