Royal Caribbean International announced on Friday it has canceled voyages on four ships because of "ongoing COVID-related circumstances around the world."
"In abundance of caution, Royal Caribbean International is pausing operations" on some ships, the company told CNN in a statement.
The cruise line said it moved forward with the cancellations despite its health and safety measures, including vaccination and testing requirements for guests and crew.
Royal Caribbean said guests booked on the canceled sailings would receive compensation options, including a full refund.
Royal Caribbean said the following four ships are affected:
• Vision of the Seas: Its return to cruising is postponed until March 7.
• Serenade of the Seas: Its sailings from January 8 to March 5 are canceled. It's returning after dry dock on April 26.
• Jewel of the Seas: Its sailings from January 9 to February 12 are canceled. It's returning on February 20.
• Symphony of the Seas: Its sailings from January 8 to January 22 are canceled. It's returning on January 29.
"We regret having to cancel our guests' long-awaited vacations and appreciate their loyalty and understanding," the statement said. "Our top priority is always the well-being of our guests, our crew and the communities we visit."
Royal Caribbean says all guests 12 and older departing US ports must provide proof of Covid-19 vaccination, with the final dose of their vaccine given at least 14 days before sailing. The cruise operator also said certificates of recovery can't be used in place of proof of full vaccination.
Rules can vary, however, depending on the port of departure, the company says on its website. Testing requirements vary by port of departure and age group.
Earlier this week, Norwegian Cruise Line said it was canceling sailings on eight of its ships in the U.S. and abroad to protect the health and safety of guests, crew members and communities.
These decisions come as COVID-19 cases have been reported on every cruise ship sailing with passengers in U.S. waters, according to the Centers for Disease Control and Prevention.
The latest CDC data shows all 92 ships with passengers currently embarked on a voyage have met the threshold for investigation by the health agency. The CDC's investigation threshold includes cases reported in 0.10% or more of passengers and at least one case involving crew members.
According to the Washington Post, this week marked the first time that every ship had reached that level of CDC coronavirus investigation.
Last week, the CDC warned everyone not to go on cruises, regardless of their vaccination status, because of onboard outbreaks fueled by the omicron variant.