Vice President Mike Pence announced Friday that the Grand Princess cruise ship off California’s coast has at least 21 people infected with coronavirus — and that all 3,522 people aboard will be tested.

Pence said the ship will be moored at a non-commercial port to facilitate testing of the passengers to ensure they do not disperse COVID-19. Only 46 people aboard the massive cruise ship were tested for the virus.

Of the infected, 19 are crew members and two are passengers. Twenty-four other people aboard tested negative and one was inconclusive, officials said at a White House briefing.

The ship, carrying 1,100 crew and 2,600 passengers, left San Francisco on Feb. 21 for a cruise to Hawaii. A planned visit to Mexico upon return was cancelled after a passenger on the ship’s previous voyage — to Mexico — died of coronavirus.

The Grand Princess had been due to return to San Francisco on Saturday.

Pence, the Trump administration’s point person on coronavirus response, said it’s likely that the crew members will remain aboard while testing is done. He said plans remain in progress for transferring passengers to military base quarantines.

Deborah Birx, Pence’s coordinator on the crisis, said: “We know many of the people on the cruise ship are in their 60s, 70s and 80s… as we know that’s a more vulnerable group that we pay special attention to … we’re working very hard with the people on the ship and the medical team there to make sure that their health and welfare is prioritized.”

Pence added: “Cruise ships present a unique challenge for health officials. And so we would ask elderly Americans to use common sense planning any cruise ”

The quarantine of another cruise ship owned by the same company, the Diamond Princess, in Japan last month resulted in spread of the virus among passengers. Health authorities condemned steps taken to mitigate that spread.

In the case of the Diamond Princess, 696 out of about 3,700 passengers and crew ultimately tested positive, of whom six have died.

The coronavirus has infected more than 200 U.S. residents, of whom 14 have died. Globally, more than 100,000 people have been infected, with more than 3,000 deaths.