Matthew Smith was feeling very good Monday about rejecting the U.S. government’s offer to be evacuated from the Diamond Princess cruise ship docked in Japan.

He had just gotten word that 14 of the 300-plus Americans and fellow passengers who had boarded a cargo plane back to the U.S. had actually tested positive for the new coronavirus.

“OMG! US Gov’t said they would not put anyone on the planes who was symptomatic, and they ended up knowingly and intentionally putting on 14 people who actually have the virus,” Smith tweeted.

“Decision not to be evacuated = best decision ever!”

Smith and his wife will remain in quarantine on the ship until the Japanese government agrees they can leave—likely this week. He said they will be tested before they disembark and then will be free to go.

All the evacuees, meanwhile, will be in quarantine for at least two weeks at Air Force bases in Texas and California—many no doubt wondering whether they, too, might suddenly fall ill.

The 14 newly diagnosed patients had been tested two to three days earlier; it wasn’t clear why the results weren’t available until they had already gotten off the Diamond Princess and onto buses to take them to the airport. (The U.S. State Department and federal health officials said they were not showing symptoms, and they decided to let them fly home in a separate chamber from the other 314 passengers.)

But the post-evacuation diagnoses are the latest surprise development in an outbreak that has mostly been centered in China but is now on the verge of becoming a global crisis, experts say.

“We’re bordering on declaration of a true pandemic,” said Dr. Irwin Redlener, director of Columbia University’s National Center for Disaster Preparedness.

“The more people we have in the general population in any country the more likely it is that we’ll declare a global pandemic internationally, which of course will pose lots of challenges to the control of the spread of the disease.”

Dr. Anthony Fauci of the National Institutes of Health told USA Today on Monday that he would not be surprised if more American evacuees get sick and that it’s clear quarantine on the Diamond Princess didn’t work.

“I mean, I’d like to sugarcoat it and try to be diplomatic about it, but it failed,” he said. “People were getting infected on that ship. Something went awry in the process of the quarantining on that ship. I don’t know what it was, but a lot of people got infected on that ship.”

“A pandemic is when you have multiple countries throughout the world that have what's called sustained transmission from person to person to person, multiple generations,” Fauci added on CBS’ Face the Nation on Sunday.

“Right now, there are 24 countries in which there were over 500. Several of them are starting to get to the second and third transmission. So technically speaking, the [World Health Organization] wouldn't be calling this a global pandemic, but it certainly is on the verge of that happening reasonably soon unless containment is more successful than it is right now.”

The challenges to containment became clear when Hong Kong's Department of Health announced it would prosecute two individuals after quarantined residents tried to leave Hong Kong despite mandated requirements. According to CNN, the two face up to six months in prison and a fine of over $3,000.

And over the weekend, authorities also revealed that an 83-year-old woman allowed to leave another cruise ship, the MS Westerdam docked in Cambodia, was sick.

It was an unexpected turn because the cruise company, Holland America, had insisted there was no sign of the virus aboard. More than 140 passengers left with the elderly woman and flew with her to Malaysia, where she felt ill and was tested.

The late diagnosis raised the question of whether she could have infected other people on or off the Westerdam. Health officials were scrambling to track down her fellow passengers so they could be monitored.

Complicating the containment effort is a lack of concrete information, Redlener said.

It’s still not clear how easily the virus can be transmitted by people who are infected but not showing symptoms, in part because the incubation period has not been pinpointed.

Testing for coronavirus, meanwhile, is still cumbersome; scientists have not yet developed a rapid-result nasal swab.

“If we’re going to stand any chance of containing this threat, it behooves us to have a test that works [and] works rapidly, because we need to identify contacts rapidly and then trace the contacts,” Redlener said.

“And we may have lost the ability to true containment if we can’t make diagnoses and we already have people with the disease in the general population.”

If an infected person who is walking around is a so-called “super-spreader,” who can transmit the virus at a much higher rate than the average person, the problem becomes exponentially worse.

Some experts believe there was a “super-spreader” aboard the Diamond Princess. And despite quarantine restrictions on board the ship, there have been 454 diagnoses—99 of them announced on Monday.

Smith, however, isn’t worried. He said he and his wife have been strictly following quarantine protocols—and enjoying the room service.