Two passengers tested positive for the coronavirus during routine checks aboard a Mediterranean cruise this week, MSC Cruises said.

The passengers, who were asymptomatic, got their positive test results on Monday, according to MSC Cruises spokesman Luca Biondolillo. They were not travelling together on the MSC Seaside. Biondolillo said the individuals and their travelling groups, as well as close contacts, were immediately isolated, and no one aside from the original two passengers tested positive.

According to the Times of Malta, the vessel was not allowed to make a regular call-in to Malta’s Valletta cruise port Monday. Instead, Biondolillo said, the ship made a “technical call” — where passengers don’t disembark — and then resumed its regular schedule with a stop in Sicily.

Both passengers and their parties left the ship in Siracusa, on the island of Sicily, and were taken home “by protected MSC Cruises transport” Tuesday, the cruise company said. The ship continued its normal schedule after the Siracusa stop.

“All of this took place in line with the protocol and in coordination with the local health authorities,” Biondolillo said in an email Wednesday.

Passengers on MSC ships are not required to be vaccinated, but they have to undergo several tests: two to three days before leaving for a cruise, just before getting on the ship and midway through the cruise, Biondolillo said.

“If anything, this is another demonstration that the protocol works,” he said.

The company started sailing in the Mediterranean in August 2020 and has seen “a handful such cases” since, Biondolillo said, adding that “many thousands” of passengers have sailed safely.

Cruise ships have slowly started service again around the world, but still have not resumed in the United States since the Centers for Disease Control and Prevention shut the industry down last March. The agency is not requiring cruise ships to sail with vaccinated passengers but will allow those with at least 95 per cent of vaccinated crew and guests to skip test cruises meant to show how they will deal with covid-19 risks.

The first cruise from U.S. shores with paying passengers is scheduled to set sail later this month. The Celebrity Cruises ship will require everyone 16 and older to be fully vaccinated — a condition that comes into conflict with a Florida law that says businesses can’t ask for proof of vaccination status.

MSC Cruises, which is headquartered in Geneva, announced this week that it plans to start short cruises on MSC Meraviglia from Miami to the Bahamas on Aug. 2. The company recently got approval from the CDC to conduct a test cruise on that vessel.

The company said it will “welcome both vaccinated and non-vaccinated guests,” with those who are not vaccinated subject to additional testing and restrictions. Rubén Rodriguez, president of MSC Cruises USA, said in a statement that he expects the majority of passengers will be vaccinated.

“The rapid distribution of vaccines in the U.S. has been a positive step toward helping vacationers get back to travelling, and we encourage our guests to take advantage of this added layer of protection when resuming travel this summer,” he said.