The number of US deaths from the novel coronavirus rose to six on Monday, all in the state of Washington, officials said, signaling the contagion has taken root in the Pacific Northwest.
Vice President Mike Pence announced a treatment for the disease could be available by summer or early fall, but that a vaccine was farther off.
Pence, the administration's pointman for the crisis, also said the government was moving to screen 100 percent of passengers flying in from Italy and South Korea, two serious virus hot zones.
Five of the six American fatalities have been from King county, the most populous in Washington state and home to Seattle, a city of more than 700,000 people. The sixth victim was from neighboring Snohomish county, officials said.
"The risk for all of us of becoming infected will be increasing," said Jeff Duchin, a health officer in King County.
"Although most of the cases will be mild or moderate, the infection can cause serious illness and there's a potential for many people to become ill at the same time." The state reported four new cases, three from the same nursing home, taking the total number of US cases to more than 90 -- about half of which were people repatriated from either China or a virus-stricken cruise ship off Japan.
Dow Constantine, the top official in King County, said his office was in talks to purchase a motel in which to place people who required isolation, adding: "We have to move to a new stage in the fight to contain, mitigate and manage this outbreak."