After four passengers arriving on a Royal Caribbean cruise ship that docked in a New Jersey port were sent to a hospital to be tested for the novel coronavirus Friday morning, the cruise line announced it was temporarily banning any travellers holding Chinese, Hong Kong or Macau passports from boarding its ships.

The cruise line said that, because of coronavirus concerns, “any guests holding a Chinese, Hong Kong or Macau passport, regardless of when they were there last, will not be allowed to board our ships” through the end of February.

Additionally, Royal Caribbean said “any guest or crewmen travelling from, to, or through mainland China, Hong Kong or Macau less than 15 days prior to their sailing will be unable to board any of our ships”.

The statement came hours after US health authorities sent four passengers arriving on the Anthem of the Seas, which had docked in Bayonne, New Jersey, just south of Manhattan, to the hospital for further tests for coronavirus.

The Miami-based company had already announced restrictions on travellers earlier this week, requiring passport holders of China, Hong Kong and Macau to go through a specialised screening process before boarding the ships.

The four people being tested were among 27 passengers who had been screened by staff from the US Centres for Disease Control and Prevention (CDC) on the ship, according to a statement by the New Jersey state government. All of those screened had recently travelled to mainland China.

Twenty-three of those passengers aboard the ship were cleared of the disease, the New Jersey statement said.

“The hospital is following proper infection control protocols while evaluating these individuals. New Jersey currently has no confirmed cases of novel coronavirus and the risk to residents remains low,” New Jersey Governor Phil Murphy said in a statement.

In its statement, Royal Caribbean said: “None of the four guests showed any clinical signs or symptoms of coronavirus while they were on-board our ship.

“One had tested positive on-board for Influenza A. Our records indicate the guests had not been in China since January 26.”

Neither New Jersey nor New York so far have any confirmed cases of the novel coronavirus, which originated in China’s Hubei province and has spread across the planet, including six US states, California and Massachusetts among them.

New York City has had five suspected cases, but tests for three of those have come back negative while the other two are pending. As of Friday, the US has 12 confirmed cases of coronavirus.

For the month of January, the CDC said, it had responded to clinical inquiries from public health officials and health care providers to assist in evaluating approximately 650 persons thought to be at risk for the infection, 210 of whom were tested.

There are currently more than 30,000 confirmed cases of the disease worldwide and more than 630 deaths, most of them in mainland China.