The California Air National Guard had delivered 46 tests to the Grand Princess, which has been offshore since Wednesday. Of the 46 passengers tested, Pence said 21 people, 19 employees and two passengers, had tested positive. Twenty-four tested negative, and one was inconclusive, Pence said.
There are over 3,500 people on board the ship, which is anchored near San Francisco.
All passengers will be brought into port in the U.S. over the weekend and tested, said Pence, who is leading the Trump administration's response to the outbreak.
"Those who need to be quarantined will be quarantined. Those who require additional medical attention will receive it," he said. Officials said crew members are likely to be quarantined aboard the ship, while passengers could be quarantined at military bases.
Pence spoke shortly after President Donald Trump, touring Centers for Disease Control and Prevention headquarters in Atlanta, told reporters that he'd rather people be kept on the ship because otherwise they'll add to the country's coronavirus statistics.
"I like the numbers being where they are. I don't need to have the numbers double because of one ship that wasn't our fault. And it wasn't the fault of the people on the ship either, ok? It wasn't their fault either and they're mostly Americans," Trump said. But, he added, he would abide by what Pence and his team of "great experts" decide.
"They would like to have the people come off. I'd rather have the people stay. But I'd go with them. I told them to make the final decision," Trump said.
The ship off California was returning to San Francisco after visiting Hawaii. Some of the passengers remained on board after sailing on its previous voyage, to the Mexican ports of Puerto Vallarta, Manzanillo, Mazatlan and Cabo San Lucas.
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"It's important to note that the Grand Princess was actually on its second tour and we know of coronavirus infections from the first tour as well, with very, very difficult results," Pence said.
A Sacramento-area man who sailed on the ship in February later succumbed to the coronavirus. Two other passengers from that voyage have been hospitalized with the virus in Northern California, and two Canadians who recently sailed aboard the ship tested positive after returning home, officials said.
Pence urged those who are vulnerable to the coronavirus, especially the elderly and people with pre-existing health issues, use "common sense and caution in planning any cruise ship vacation in the future."
Trump was asked about delays in testing around the country, and he suggested the problem had been solved.
"Anybody, right now, and yesterday, anybody that needs a test gets a test," he said. "They're there, they have the tests.”
He then made an odd reference to the phone call with the Ukrainian president that helped lead to his impeachment. "The tests are all perfect. Like the letter was perfect. The transcription, was perfect. This was not as perfect as that, but pretty good,” he said.
Pence and the members of the coronavirus task force, speaking in the White House briefing room, said the government had sent out 900,000 tests this week, with 200,000 more to be sent Saturday — short of the 1.5 million tests initially projected to be delivered by the end of this week. Pence said the expectation was that by the end of next week, another 4 million tests would be shipped.
Trump and Pence also differed on the subject of Washington Gov. Jay Inslee, who tweeted last month that the administration would be more successful combating the coronavirus "if the Trump administration stuck to science and told the truth."
Pence visited Washington, the state hardest hit by the coronavirus, on Thursday, and met with Inslee. Pence said they'd been working together "in a seamless way" and Inslee said they have "a very good partnership" with the federal government.
"I told Mike not to be complimentary to the governor because that governor is a snake," Trump said. "Mike may be happy with him, but I'm not."
Inslee responded to the president on Twitter.
"My single focus is and will continue to be the health and well-being of Washingtonians. It's important for leaders to speak with one voice. I just wish the president and vice president could get on the same page," he wrote. "We appreciate the vice president's visit and our teams are working well together."