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Only 20 patients were being treated Thursday on the USNS Comfort hospital ship that docked in New York Harbor earlier this week to aid in the coronavirus fight.

The vessel’s captain, Patrick Amersbach, said in a call with reporters Thursday morning that only three of the 1,000 beds on the ship were put in use since the first patient was accepted Wednesday — but he expected the number to increase soon.

A Navy spokeswoman on Thursday night updated the number to 20.

“The process continues and we are honestly looking forward to seeing a significant increase in patients being transferred to the Comfort,” Amersbach said, adding that each patient must be referred to the ship by a local hospital.

Another US Navy hospital ship, the USNS Mercy, docked in Los Angeles, had a total of 15 patients, that vessel’s captain, John Rotruck, said on the call.

Rather than take on victims of the pandemic, both ships were brought in to treat patients with other injuries and ailments, freeing up beds in overwhelmed hospitals for those who need them most.

But a load of bureaucratic hurdles and military protocols has kept the Comfort from accepting many patients, according to the New York Times.

“If I’m blunt about it, it’s a joke,” Michael Dowling, the head of New York’s Northwell Health hospital system, told the Times.

“Everyone can say, ‘Thank you for putting up these wonderful places and opening up these cavernous halls.’ But we’re in a crisis here, we’re in a battlefield.”

Among the roadblocks is that the Navy is refusing to treat people with a host of other medical conditions besides COVID-19, the Times reported.

Also, ambulances can’t take patients directly to the ship — they must first be taken to a city hospital for evaluation, including a test for the virus, and then picked up again and brought to the vessel.

Given the destructive spread of the disease in the Big Apple, where nearly 50,000 were infected as of Thursday, it is pointless to try to divide patients between those who have it and those who don’t, Dowling and other hospital leaders said.

The solution would be to open the Comfort to COVID-19 patients, the hospital leaders said.

“It’s pretty ridiculous,” Dowling said. “If you’re not going to help us with the people we need help with, what’s the purpose?”

A newly opened makeshift hospital in the Javits Center was also originally expected to only treat non-coronavirus patients.

But President Trump on Thursday approved Gov. Andrew Cuomo’s request that the medical center be used to care for New Yorkers with the virus.

The patients currently being treated at the Manhattan convention center are expected to be transferred to the Comfort, though it’s unclear when.