China cautioned on Wednesday that a SARS-like virus could mutate and spread with the death toll rising to nine and the number of cases reaching 440 across the country.

The coronavirus is transmitted through the respiratory tract and there is “the risk of viral mutation and further spread of the disease,” vice minister of the National Health Commission Li Bin said during a news conference.

The commission announced measures to contain the disease as hundreds of millions of people travel throughout the country for the Lunar New Year holiday this week, including disinfection and ventilation at airports, train stations and shopping centers.

“When needed, temperature checks will also be implemented in key areas at crowded places,” the commission said in a statement.

Some other Asian countries have detected the virus and the United States confirmed its first case on Tuesday.

The origin of the outbreak is in Wuhan’s central Chinese city, where authorities have stepped up fever checks at the airport, train stations, and highways, while a big Lunar New Year celebration has been cancelled, drawing hundreds of thousands of people.