“This is a worrying and serious situation and investors must be vigilant,” he added.

The concern is that the fallout could create a major shock for markets, even as worries about geopolitics and global trade have eased.

Many Asian stock markets were closed for the Lunar New Year holiday, but those that were open, including Japan’s and South Korea’s, fell and futures trading in China slumped. Money poured into safe-haven assets like gold and pushed up the value of the United States dollar. Most European markets were slightly higher.

Japan’s minister of economic and fiscal policy said on Tuesday that the Chinese outbreak would affect the Japanese tourism industry and warned that it could also hurt exports and corporate profits. Chinese tourists traveling to Japan accounted for 30 percent of all tourists in 2019, he said at a news conference.

“There are concerns over the impact to the Chinese and global economy from the spread of infection in China, transportation disruptions, cancellation of group tours from China and an extension in the Lunar holiday,” said the minister, Yasutoshi Nishimura.