A Florida couple who was aboard the coronavirus-hit Grand Princess ocean liner has sued the ship's owner for more than $1 million, claiming the company put profits over safety and did not have proper screening protocols in place.

Ronald and Eva Weissberger of Broward County, Florida sued Princess Cruise Lines Ltd, a unit of Carnival Corp, alleging the company caused them emotional distress and trauma as they fear they will develop the COVID-19, a flu-like disease caused by the virus.

The Weissbergers said Princess Cruise lacked a proper screening protocol to minimise the risk of passengers' exposure.

The lawsuit was filed in US District Court in Los Angeles.

Carnival did not immediately respond to a request for comment.

The Grand Princess docked in Oakland, California, on Monday so its 2,400 passengers could disembark and be taken to quarantine or medical sites. An initial round of testing aboard the ship last week found that 21 people, mostly crew, were infected with the coronavirus.

The ship has been linked to 12 coronavirus cases from an earlier voyage to Mexico. The Weissbergers, who boarded the ship on February 21 when it departed from San Francisco, were still passengers on the Grand Princess when the lawsuit was filed, according to the complaint.

They claim passengers were only asked to "fill out a piece of paper confirming they were not sick" without being further questioned or screened prior to boarding.

"Defendant Princess chose to place profits over the safety of its passengers, crew and general public in continuing to operate business as usual, despite their knowledge of the actual risk of injury to plaintiffs, who are elderly with underlying medical conditions," the complaint said.

On Wednesday, the Grand Princess was denied entry to San Francisco Bay as it sailed back from Hawaii after state and local health authorities learned that some passengers from an earlier cruise on the same ship had developed flu-like symptoms.

The ship was allowed to dock in Oakland on Monday.

The lawsuit said that the cruise operator should have developed methods for protecting passengers due to its experience with another of its cruise liners, the Diamond Princess, which was quarantined in Japan. About 700 aboard that ship became infected and seven passengers died.

The complaint did not identify the Weissbergers' medical conditions or provide their ages.

Princess is refunding passengers the full price of the cruise plus air travel, hotel, ground transportation and pre-paid shore excursions.

Another Princess cruise ship kept at sea pending virus tests

Thousands of passengers on an additional Princess Cruises ship are being kept on board while crew members get tested for COVID-19. 

The Caribbean Princess, on a 10-day trip to the Panama Canal, was scheduled to dock in Grand Cayman on Monday. But the California-based cruise line said it will keep passengers and crew from disembarking, and instead will pick up test kits after notifying the CDC that two crew members had transferred from a Princess ship in California where a guest had tested positive for COVID-19.

These crew members being tested are currently "asymptomatic" and are remaining alone in their rooms “out of an abundance of caution" as the ship returns to Fort Lauderdale, the company statement said.

The ship is under a “no sail order” from the US Centers for Disease Control and Prevention, requiring it to remain at anchor off the coast of Florida until further notice, the statement said. It was originally scheduled to return Wednesday to Fort Lauderdale.

The Regal Princess underwent a similar process, spending most of a day sailing up and down the Florida coast, before finally pulling into Port Everglades late Sunday.

Its passengers finally disembarked after two crew members tested negative for the coronavirus. Those crew members also lacked symptoms, but had come from the Grand Princess in California, where at least 21 people tested positive. 

Last month, Japanese authorities quarantined the Diamond Princess cruise ship off the port of Yokohama for a harrowing two weeks after 10 passengers were initially diagnosed with the disease. 

Many countries, including the United States, evacuated their residents from the ship, and Japan drew criticism for keeping people on board. In the end, nearly 700 people among the 3,700 passengers tested positive for the disease, and at least six people have died.

The US State Department advised Sunday against any travel on cruise ships, particularly for those with underlying health conditions. The advisory said the CDC has noted an “increased risk of infection of COVID-19 in a cruise ship environment.”

It is unclear how many people have been on board the Florida-based ships. The cruise line said the Regal Princess has a capacity of 3,560 guests and the Caribbean Princess can carry more than 3,600 guests.

Passengers began disembarking shortly after the Regal Princess pulled into port, the South Florida Sun Sentinel reported.

Penny Sitz, of Minnesota, said the crew was “fantastic,” constantly cleaning and “making us wash our hands all the time.”

The Regal Princess had been scheduled to return to sea on a seven-day Caribbean trip on Sunday, but that voyage was cancelled. The cruise line said guests would receive a full refund and offered $300 reimbursement for one night's hotel costs. 

The cruise line hasn't announced plans for the next Caribbean Princess voyage. A cruise on the same ship was cut short last month after a gastrointestinal outbreak sickened at least 299 passengers and 22 crew members.

Cruise industry leaders met over the weekend with Florida Governor Ron DeSantis and Vice President Mike Pence and were asked to devise and fund ways to transport any passengers found to carry the virus. 

Cruise line heads agreed to enhance entry and exit screenings and establish shipboard testing, along with new quarantine standards established by the CDC. Some of the new protocols were expected to start taking effect early this week.

The vast majority of people recover from the new virus.

According to the World Health Organization, people with mild illness recover in about two weeks, while those with more severe illness may take three to six weeks to recover. In mainland China, where the virus first exploded, more than 80,000 people have been diagnosed and more than 58,000 have so far recovered.