About 500 passengers have left the Diamond Princess cruise ship at the end of a two-week quarantine that failed to stop the spread of coronavirus among passengers and crew.

Authorities announced 79 more cases on the ship, docked in Japan, bringing the total to 621.

Results were still pending for some other passengers and crew among the original 3,711 people on board the vessel.

Japan’s government has been questioned over its decision to keep people on the ship, which some experts have called a perfect virus incubator.

A bus carrying the passengers from the quarantined Diamond Princess cruise ship leaves a port in Yokohama, near Tokyo
A bus carrying passengers from the Diamond Princess cruise ship leaves port in Yokohama, near Tokyo (Eugene Hoshiko/AP)

The Diamond Princess is the site of the most infections outside of China, where the illness named Covid-19 emerged late last year.

Many foreign governments say they will not let passengers from the ship return unless they go through another quarantine period, so it was striking to see passengers disembark, get into taxis and disappear into Yokohama, where the ship is docked.

Japanese soldiers helped escort some passengers, including an elderly man in a wheelchair who wore a mask and held a cane.

Some passengers got on buses to be transported to train stations.

Some people still in their cabins waved farewell from their balconies to those who had already been processed.

“I’m a bit concerned if I’m OK to get off the ship, but it was getting very difficult physically,” a 77-year-old man from Saitama, near Tokyo, who got off with his wife, told Kyodo News.

“For now, we just want to celebrate.”

Health minister Katsunobu Kato said initially on Wednesday that those disembarking with negative virus tests have fulfilled the Japanese quarantine requirement and are free to walk out and go home on public transportation.

He said passengers were only asked to watch their health carefully for a few days and notify local health authorities if they have any symptoms or worries.

A passenger in a wheelchair is escorted after he disembarked from the quarantined Diamond Princess cruise ship in Yokohama, near Tokyo
A passenger in a wheelchair is escorted after disembarking from the Diamond Princess (Jae C Hong/AP)

But after meeting with experts later in the day, he urged the former passengers to refrain from non-essential outings and try to stay home for about two weeks.

“Covid-19 is not 100% known, and a lot of people got infected on the Diamond Princess. Taking those factors into consideration, we believe taking extra caution will contribute to preventing the risk of future infections,” he said.

Some passengers said on Twitter they received health forms asking if they had symptoms such as a headache, fever or coughing.

Passengers who tested negative and had no symptoms still had to get their body temperature checked before leaving.

About 500 passengers who planned to leave on Wednesday had all left the ship by evening, and Japanese officials are to spend the next three days conducting the disembarkation of about 2,000 others.

The Diamond Princess was quarantined in Yokohama near Tokyo after one passenger who left the ship earlier in Hong Kong was found to have the virus.

Even though Japanese officials insist the number of infected patients is levelling off, cases on the ship continue to mount daily.

On Tuesday, 88 people tested positive, a day after 99 others were found to be infected.

A bus carrying passengers from the quarantined Diamond Princess cruise ship leaves a port in Yokohama, near Tokyo
A bus carrying passengers from the ship leaves port (Eugene Hoshiko/AP)

Crew members, who could not be confined to their rooms because they were working, are expected to stay on the ship.

The National Institute of Infectious Diseases said in a report released on Wednesday that the crew had not been fully isolated during the quarantine period.

It said the quarantine was effective in reducing transmission among passengers, and that the increase in cases towards the end was mostly among crew or passengers in shared cabins.

“It should be noted that due to the nature of the ship, individual isolation of all those aboard was not possible,” it said.

Some medical experts who assisted with the quarantine have said anti-infection measures were often sloppy on the ship.

Four health workers – a quarantine official, a doctor, a paramedic who took an infected passenger to hospital and a health ministry official assigned to quarantine paperwork on the ship – became infected.

Chief cabinet secretary Yoshihide Suga said a more controlled health watch for the crew members is starting now because they can be spread out and kept in isolation by using vacated passenger rooms.

He acknowledged that crew members were not in adequate quarantine until now, but said they took as many preventive measures as they could.

The quarantined Diamond Princess cruise ship is anchored at a port in Yokohama, near Tokyo
The quarantined Diamond Princess cruise ship (Yuta Omori/Kyodo News via AP)

The ship’s operator, Princess Cruises, said in a statement on Tuesday that people who tested positive recently were still on the ship as they waited for transportation to hospitals.

The safety and transport logistics for moving hundreds of people will test Japanese officials.

The United States evacuated more than 300 people over the weekend who are now in quarantine in the US for another 14 days.

South Korea earlier on Wednesday returned seven people from the cruise ship, placing the six South Koreans and one Japanese family member into quarantine.

Other foreign passengers were to be picked up by chartered flights sent from Canada, Australia, Italy and Hong Kong.

Japanese health officials say the 14-day quarantine on the ship was adequate, noting that all but one of more than 500 Japanese who earlier were flown back from the centre of the virus in China and initially tested negative were virus-free at the end of their 14-day quarantines.

The officials also defended the precautions taken on the ship.

About 1,000 crew members were told to wear surgical masks, wash their hands, use disinfectant sprays and stop operations at restaurants, bars and other entertainment areas after February 5, when the first group of 10 infections was reported and the start of the 14-day quarantine was announced.

A passenger is directed in a car park after disembarking from the quarantined Diamond Princess cruise ship in Yokohama, near Tokyo
A passenger is directed in a car park after disembarking from the ship (Jae C Hong/AP)

Passengers were instructed to stay in their cabins and not walk around or contact other passengers.

Those in windowless cabins could go out on the deck for about an hour each day.

The quarantine was largely for passengers because crew members kept sharing double rooms and continued to serve guests by delivering food, letters, towels and amenities, and entering passenger cabins for cleaning.

Crew members also ate in groups in a crew mess hall.