Update: Iwata has since removed his YouTube video, saying there is “no need for further discussing this.”

Kentaro Iwata, an infectious diseases expert at Kobe University, was brought onto the Diamond Princess yesterday, a day before the Japanese government began allowing passengers to disembark from the quarantined cruise ship. What he saw shocked him.

“The cruise ship was completely inadequate in terms of the infection control,” Iwata said in a YouTube video he uploaded yesterday. “There was no distinction between the green zone, which is free of infection, and the red zone, which is potentially contaminated by the virus.” He had boarded the ship as a member of the disaster medical assistance team, after having been denied permission to enter in his own capacity as an infection control expert, he said.

The ship has been docked off the port city of Yokohama since Feb. 3, with 3,700 people onboard. A man who disembarked in Hong Kong on Jan. 25 was found to have Covid-19, prompting the quarantine. The ship is operated by Princess Cruises, part of the Carnival Corporation, one of the world’s largest cruise companies.

As the number of people infected on the vessel steadily crept up, experts began questioning Japan’s strategy of continuing to enforce the quarantine on thousands of people in an enclosed space. While passengers were confined to their cabins, crew members shared living and working spaces and had minimal protective gear when interacting with passengers. As of yesterday, 542 people have been confirmed infected with coronavirus, or roughly 15% of everyone onboard.

Passengers who tested negative for Covid-19 and who have been asymptomatic began disembarking this morning, though people who tested negative but shared a room with an infected person will be kept aboard for additional quarantine.

Iwata said in the video that in his two decades of dealing with infectious diseases, including the 2003 SARS outbreak in China and the more recent Ebola outbreak in Africa, he “never had fear of getting infection myself.” But on the Diamond Princess, he said, “I was so scared. I was so scared of getting Covid-19 because there’s no way to tell where the virus is. No green zone, no red zone, everywhere could have the virus.” He added that “there was was nobody in charge of infection prevention as a professional, the bureaucrats were in charge of everything.”

In his day spent aboard the ship, Iwata said he observed numerous lapses in infection control measures. Crew members, some of whom were wearing full protective gear and others who weren’t, were walking around the vessel, potentially cross-contaminating different parts of the ship, he said. Iwata said he also saw people eating lunch with their medical gloves on, and handling their smartphones while wearing their protective suits, “so it was completely chaotic.”

Even something as simple as a printed informed consent form to authorize tests for coronavirus is a potential source for transmission, Iwata said. “That paper was going back and forth, back and forth” between the room with the infection and elsewhere, he said, describing how his suggestion to switch to verbal informed consent was neglected. He was later ordered off the ship by someone from the ship’s quarantine office, he said. He has isolated himself in a separate room to avoid infecting his family.

In a series of tweets (link in Japanese), vice minister of health Gaku Hashimoto, who was on board the ship, said Iwata couldn’t give him a clear answer as to why he was on board and so was politely asked to leave the vessel. Hashimoto added that he’ll report the incident back to the health ministry to understand how this was able to happen.

Addressing Iwata’s comments, an official from the ministry of health and labor told Japanese newspaper Asahi Shimbun (link in Japanese) that it was a “misconception” that amateurs rather than specialists are working on board the ship to prevent infections.

Correction: An earlier version of this story misstated that people who tested positive but shared a room with an infected person will be quarantined. It should be those who tested negative.