Ports around the U.S. are rolling out vaccines for seafarers, extending a lifeline to thousands of mostly foreign workers who've spent the pandemic isolated aboard ships ensuring goods kept trading across a battered global economy.

From Boston to Houston and Los Angeles, and even in smaller trade gateways like Gulfport, Miss., local health officials and nonprofits are boarding container ships, tankers and other cargo carriers to administer COVID-19 shots or, when possible, shuttling crews to nearby pharmacies and clinics.

The preferred vaccine for maritime workers: the one-dose Johnson & Johnson shot, because they're often docked for just a day or two.

In Los Angeles and nearby Long Beach, Calif., home of the nation's largest port complex, a vaccination program that began in mid-May has reached about 500 visiting sailors on 11 container ships as of late last week, city spokeswoman Chelsey Magallon said.

Similar efforts are getting underway at nearly 50 U.S. seaports, according to a list maintained by the North American Maritime Ministry Association.

Throughout the pandemic, seafarers have suffered a doubly harsh form of cabin fever. Travel restrictions prevented crew changes, forcing many to stay aboard beyond their original contracts and the 11-month limit set by maritime law. They've also been banned from disembarking in port for fear of spreading COVID or putting their vessel into quarantine for a week or more at the expense of millions of dollars.

"That's a very big deal for sailors because they are essentially stranded aboard ships," said Dick McKenna, president of the International Seafarers Center of Long Beach-Los Angeles, a hospitality club that offers logistics on land like Wifi, shopping or health-care services. "Some of these guys have been out there for like a year -- the suicide worry is high. The shots are a really big boost."

Many of the world's 1.6 million seafarers hail from poor countries like India and the Philippines that have struggled to inoculate citizens as quickly as the U.S., where vaccines remain abundant.

"It's a huge welcome relief for these ships because all these foreign countries are having a hard time giving vaccines," said Tom Jacobsen, who runs a pilot service at the Port of Long Beach.

About 400 miles north on the California coast, Oakland's port is averaging vaccines for about 80 seafarers a day and offering them either on the ship or in a clinic, said John Claassen, chairman of Oakland's International Maritime Center. Some recipients view their vaccine certificates "like a 'get out of jail free' card," he said.

In the Philadelphia area, some 22 crews totaling 258 seamen had been vaccinated as of Saturday, courtesy of rides to local pharmacies, said Helene Pierson, executive director of the Seamen's Church Institute of Philadelphia and South Jersey. "I'm averaging about 20 crew a day and about 10 ships a week," she said.

Some sailors are stepping foot on land for the first time in nine months or longer.

"We are on a continuous rotation between six ports in the USA and six ports in Brazil and one in Argentina and Uruguay -- a vaccination would help us a lot," Ingmar Koal, the master on board the container carrier the Northern Majestic, wrote in an email to Pierson on May 18 as the ship approached Philadelphia.

Complicating the local efforts to deliver the vaccines are safety rules that require at least half the crew to remain aboard the ships -- so the shuttles often have to make two or three trips between the port and drugstore. Other potential snags: many workers' visas have expired, which prevents them from leaving the ship, or face U.S. Customs and Border Protection rules against the arrival citizens of certain countries.

Despite coordination efforts that are "still extremely challenging," 130 seafarers were vaccinated in 10 days in Delaware, according to Christine Lassiter, executive director of the Seamen's Center of Wilmington.

For crews who might come from Eastern Europe or Southeast Asia, there's an economic incentive to get a vaccination card.

"That card and paperwork are going to make them very marketable," said Stefan Mueller-Dombois, an inspector with the International Transport Workers' Federation in Long Beach. "Their company will want them back or they can find another ship to work on really easily."

In other parts of the world, more COVID outbreaks have stricken crew on ships and once again closed off some ports, particularly vessels carrying Indian crews or having recently traveled to India.

That's why a global vaccination program supported by a number of governments is key to resolving the crisis at sea, said Rene Kofod-Olsen, chief executive officer of ship and crew manager V.Group Ltd. The company recently completed its first vaccinations in the U.S. -- 13 Indian seafarers aboard the Cabrera in Port Everglades, Florida, received jabs during a stop there.

"This crisis is not over yet and we all need to keep the gas up on this," Kofod-Olsen said.

Captain Rajesh Unni, founder of Singapore-based ship manager Synergy Marine Pte Ltd., said the company expects crews on about 70 of its vessels bound for U.S. ports to be vaccinated this quarter -- just about 10% of its total pool of seafarers. "In the short term, we need to get seafarers vaccinations in countries where there are established programs and sufficient supplies of vaccines, like in the United States," he said.

What's unique about the vaccine programs in the U.S. is the broad inclusion of foreign workers, said Jason Zuidema, general secretary of the International Christian Maritime Association, a U.K. organization that represents seafarer centers globally.

China and Russia have offered doses to their domestic maritime industries, and U.K. officials have offered them to British fishermen. The Netherlands is launching a program starting in mid-June, available to seafarers on vessels flying the Dutch flag. Australia has vaccinated a small number of foreign deckhands that transport gas between the nation's ports on a ship that's under charter to energy giant Origin Energy Ltd.

Zuidema estimated that 4,000 seafarers have been vaccinated around U.S. ports in recent weeks.

"This transforms their lives and we've seen that it has almost immediate effect," Zuidema said. He added that a container ship calling on ports along the U.S. East Coast recently rewarded its fully vaccinated crew with something they haven't had since the pandemic began: shore leave.