The deadly new coronavirus continued to spread Tuesday, with more than 20,600 cases confirmed in more than two dozen countries, the vast majority in China. There have been at least 427 deaths from the flu-like illness, all but two of them in mainland China.

There were 11 cases confirmed in the U.S. as of Tuesday, including six in California, one in Washington state, one in Arizona, two in Illinois and one in Massachusetts. More than 80 other Americans were being tested for the virus.

The U.S. government declared a public health emergency last week and barred foreign nationals from entering the country within two weeks of visiting China, unless they are immediate family members of U.S. citizens or permanent residents. The State Department has warned Americans against all travel to China, and is planning more evacuation flights to bring Americans home from the country this week. Those new evacuees, along with anyone else who is allowed into the U.S. after recently being in China’s Hubei province, will quarantined for two weeks. 

Chinese officials have agreed to let American experts into the country as part of a World Health Organization team in the coming days, and senior members of the Communist Party have admitted “shortcomings and deficiencies” in the country’s response. President Xi Jinping declared “a people’s war of prevention” against the epidemic Tuesday, threatening punishment for anyone deemed to be neglecting their duties as control efforts rampedup.