As part of an effort to control the spread of COVID-19 onboard cruise ships, a number of cruise lines are requiring passengers to have proof of a booster shot prior to boarding their vessels.

Starting on March 1, cruise lines Lindblad Expeditions, Silversea and Azamara will require passengers to be fully vaccinated and have a booster shot to sail on its ships, if eligible.

Azamara currently requires all passengers to be fully vaccinated at least 14 days before sailing with the cruise line, in addition to having a negative COVID antigen test at the terminal before boarding the ship. The cruise line accepts vaccines and boosters “fully approved or authorized for emergency use” by the Food and Drug Administration or the European Medicines Agency.

Lindblad’s new booster shot policy will affect all passengers 12 and older who completed their primary vaccination series more than five months earlier, Travel & Leisure reported.

Silversea implemented a COVID booster shot policy that mandates passengers to have a booster shot if the required time has passed after completing their vaccination dosage series. The cruise line accepts vaccines that are “fully approved or authorized for emergency use” by the FDA or the World Health Organization.

Silversea also requires all passengers to wear face masks in all indoor public areas, in terminals, and during shore excursions. They must also have a negative COVID rapid antigen test before boarding and are provided a free rapid antigen test for disembarkment.

UnCruise Adventures will also require booster shots starting Feb. 5. Hapag-Lloyd Cruises' booster shot requirement goes into effect in mid-February.

Viking cruises are already requiring eligible passengers to show proof of a COVID booster shot prior to boarding its ships. 

Also adding a booster shot requirement to some or all sailings are Grand Circle Cruise Line and Overseas Adventure Travel.

The more stringent booster shot requirements come as the Centers for Disease Control and Prevention has warned Americans against cruise travel, saying that doing so puts them at a “very high” risk for contracting and spreading COVID-19, even if fully vaccinated.

P&O Cruises and Cunard Line also issued booster shot policies, according to The Points Guy.

The Viking Line cruise ship Viking Grace ran aground with some 300 passengers on its way from Finland to Sweden The Viking Line cruise ship Viking Grace ran aground with some 300 passengers on its way from Finland to Sweden Photo: Lehtikuva / Niclas Nordlund