Carnival Cruise Line is offering passengers up to $200 worth of extra credit if they keep their bookings through May 31.

Guests who choose to keep their bookings will receive the money as onboard credits, which function like money and can be used on drinks, excursions, and other purchases on board.

The cruise giant is also allowing passengers who decide to cancel their trip to move their booking to a new date and receive future credit in the amount of the nonrefundable cancellation fee.

Last month, the Diamond Princess ship, operated by the Carnival subsidiary Princess Cruises, was quarantined for two weeks in Japan after passengers tested positive for the novel coronavirus. More than 700 passengers have been infected since.

More recently, the Grand Princess, also operated by Princess Cruises, has been docked off the coast of San Francisco as US health authorities investigate coronavirus cases associated with the ship's previous voyage.

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Carnival Cruise Line is offering passengers up to $200 worth of extra credit if they keep their bookings through May 31 as the cruise industry takes a hit over concerns about the new coronavirus.

The cruise giant sent out a letter to passengers Thursday informing them of several options they could take if their vacations had been planned between March 6 and May 31.

Guests who choose to keep their coming bookings will receive the money as onboard credits, which function like money and can be used for drinks, excursions, and other purchases on board.

Here's how the credits will be distributed

$100 credit a cabin for passengers on three- or four-day cruises

$150 credit a cabin for those on five-day cruises

$200 credit a cabin for those on six-day or longer cruises

The credit will be automatically applied to the passengers' accounts, the cruise line said.

The Carnival Breeze, another Carnival Cruise Line ship. It has not been linked to COVID-19 cases. Flickr/CarnivalPR

The cruise line also provided additional rescheduling options in case some holidaymakers chose to postpone their travels until after the coronavirus becomes less of a public-health threat.

Guests who booked before March 6 and decide to cancel their trip will be allowed to move their booking to a new date and receive a future credit in the amount of the company's nonrefundable cancellation fee.

The credit must be used before March 31, 2021.

Family members of Diamond Princess passengers during its quarantine at Daikoku Pier Cruise Terminal in Yokohama, Japan, on February 11. Reuters/Issei Kato

The company's policy shift comes after several of its ships were affected by the coronavirus.

The Diamond Princess cruise ship, operated by the Carnival subsidiary Princess Cruises, was quarantined for two weeks in Japan's Yokohama port last month after several passengers tested positive for the coronavirus.

In total, more than 700 passengers from the ship have tested positive for the virus, and six people have died from the illness COVID-19.

More recently, the Grand Princess cruise ship, also operated by Princess Cruises, has been docked off the coast of San Francisco as the US Centers for Disease Control and Prevention investigates coronavirus cases associated with the ship's previous voyage.

A stock image of the Grand Princess cruise ship. Princess Cruises

On Wednesday, California announced its first coronavirus death: a passenger who had traveled aboard the Grand Princess last month. Princess Cruises has said there are currently no confirmed cases of COVID-19 aboard the ship.

Carnival shares took a major hit Thursday amid coronavirus panic, tumbling as much as 15%. Its market value has plunged by nearly 50% since the coronavirus outlook started.

The US has reported at least 232 coronavirus cases across 19 states, including 61 in California.

Twelve people in the US have died from the coronavirus: 11 in Washington state and one in California.