The US Navy hospital ship Comfort arrived in New York City on Monday to lend help to the city's overburdened hospitals during the coronavirus outbreak.

USNS Comfort's mission is to free up space in local hospitals by taking non-coronavirus patients.

But as of Thursday evening, just 20 patients were being treated, The New York Times reported. The ship has space for 1,000 patients.

The ship's low intake is partly attributable to strict restrictions over the way patients are admitted on board, the fact the Comfort isn't allowing 49 other ailments, and the lack of non-coronavirus patients in the city so far.

One hospital director told The Times the Comfort's mission was "a joke" because it wasn't helping in a meaningful way.

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The US Navy hospital ship Comfort arrived in New York City on Monday to help the city's hospitals, which have been stretched thin by the coronavirus outbreak.

It was a beacon of hope for New Yorkers, many of whom broke self-isolation and crowded the streets on the city's West Side to see the ship as it came into port.

The 1,000-bed hospital ship's mission was to free up space in the city's hospitals by taking non-coronavirus patients off their hands.

But as of late Thursday, just 20 patients were being treated on board the ship, according to The New York Times, in part because of strict rules over how patients are admitted, and because there aren't many non-coronavirus patients in the city at the moment.

New Yorkers at Pier 90 during the arrival of the USNS Comfort on Monday. Kathy Willens/AP

To get on the ship, patients must first be taken to a hospital, where they are tested for COVID-19.

But the ship isn't accepting patients with 49 other ailments as well, according to a list sent to the local hospitals.

Only once a person's issues are determined to fit the scope of the ship's treatment offerings can that person be taken by ambulance to the Comfort.

"We are honestly looking forward to seeing a significant increase in patients being transferred to the Comfort today," Capt. Patrick Amersbach, the Comfort's campaign, said during a Thursday conference call with the media.

One hospital director called the ship "a joke," suggesting it wasn't actually helping the city's hospitals in a meaningful way if would not accept COVID-19 patients.

"If I'm blunt about it, it's a joke," said Michael Dowling, the head of New York's largest hospital system, Northwell Health. He told The Times he'd had to tear his hospitals apart, turning lobbies and conference rooms into wards to treat hundreds of coronavirus patients.

"It's pretty ridiculous," he told The Times. "If you're not going to help us with the people we need help with, what's the purpose?"

Capt. Amersbach added at a news conference that if the ship's mission were changed and it was asked to accept COVID-19 cases, it would reconfigure the ship to make it happen.

"If our mission shifts, we do what we can to meet that mission," he said.

Vice President Mike Pence aboard the USNS Comfort in 2019. Joe Skipper/Getty Images

The US Navy did not immediately respond to Business Insider's request for comment.

However, a Department of Defense news release on Thursday seemed to suggest that ships were purposely making a slow start.

Capt. John R. Rotruck, who is heading a Navy hospital ship sent to Los Angeles, the USNS Mercy, said the goal was to open the hospital ships up before there was a huge need from local hospitals, so that they could establish relationships with local health systems and perfect transfers of patients.

"When the capacity demand really increases, we'll be ready," Rotruck said.