ORLANDO, Fla. — One of the world's largest cruise lines is now requiring COVID-19 vaccinations for most passengers sailing from ports along the Atlantic or Gulf coasts — including Florida.

Carnival Cruise Lines says starting Aug. 28, cruise guests over the age of 12 will now need to be fully vaccinated against COVID-19, unless they have a medical condition that does not allow them to be vaccinated. Guests must provide proof of age or medical exemption at the time of check.

Carnival Cruise Line says the vaccine requirement is needed because more places are changing regulations for cruise ships sailing into ports outside the United States. Last week, The Bahamas announced that any ship wishing to enter a Bahamian port must confirm that all guests 12 and older are fully vaccinated, aside from anyone with a medical exemption. 

"Given the number of itineraries that include multiple destinations throughout the Caribbean and, in particular, in The Bahamas, and the need for us from time to time to adjust itineraries due to medical, technical or weather emergencies, we will now operate all sailings under this requirement," said a statement on the Carnival website.

The decision will be an especially big change in Florida, which has some of the busiest cruise ports in the world.

Florida Governor Ron DeSantis banned vaccine passports and refused to allow an exemption for the cruise industry. Norwegian Cruise Line sued the state over the ban. A federal judge temporarily blocked the vaccine passport ban, but the state is appealing the ruling. 

Norwegian has threatened to pull out of Florida ports if the ban were allowed to continue.

Cruise lines leaving from ports in other states have some vaccine requirements already.

However, Carnival says if you have an upcoming cruise after Aug. 28 and you've already received exemption approval, that exemption is no longer valid. Anyone who needs help rebooking their trip or getting a refund should contact their travel agent or Carnival at 1-800-CARNIVAL.