The Ruby Princess cruise ship was docked for disinfection at San Francisco's Pier 27 Thursday morning after a norovirus outbreak affected dozens of passengers and crew.
The outbreak was reported to the CDC on Thursday, during the cruise ship's April 28 to May 11 voyage.
The CDC has activated its Emergency Operations Center and classified a hantavirus outbreak as a Level 3 response, the agency's lowest level of emergency activation, signaling a low risk to the general public.
More than two dozen people from at least 12 different countries left a cruise ship hit by a deadly hantavirus outbreak without contact tracing, officials say
An epidemiologist from the World Health Organization said that the suspected hantavirus cluster aboard a cruise ship is not the beginning of another COVID-19 pandemic.
California is one of five states monitoring people who previously traveled on the MV Hondius cruise ship, where a cluster of hantavirus cases turned deadly.