(Updated 12:22 p.m. EDT) -- Several cruise lines have begun quietly modifying their policies to prohibit those passengers who have been vaccinated with two different types of vaccines.
On Thursday, Holland America Line, Norwegian Cruise Line and Princess Cruises all modified their Health and Safety protocols to exclude those who had received mixed COVID-19 vaccinations, noting those who recieved AstraZeneca plus another vaccine would now be considered unvaccinated and unable to sail.
The move has left many Canadians and Brits who received mixed doses alongside AstraZeneca upon the recommendations of their home countries wondering what will happen to their cruises.
There are caveats, as each line is releasing slightly different policies.
Holland America Line says passengers who have had one dose of a vector vaccine like AstraZeneca, and one mRNA vaccine (like Pfizer) will not be considered vaccinated. But passengers who have received two different mRNA vaccines (Pfizer/Moderna) will be.
Princess released similar guidance, writing on its website that, "Guests who have received one single dose of a vector vaccine (e.g. AstraZeneca) and one single dose of a mRNA vaccine (e.g. Pfizer/BioNTech, Moderna) will not be considered fully vaccinated. Guests who have received two single doses of mixed vaccines that are the same type (e.g., mRNA) will be considered fully vaccinated and will be permitted to sail, so long as the final dose is received at least 14 days prior to the beginning of the cruise."
Carnival Cruise Line has also banned the use of mixed vaccinations that involve at least one dose of AstraZeneca.
Norwegian Cruise Line, on the other hand, states on its website that any vaccine mixing will result in passengers being considered unvaccinated. Norwegian's rules only apply to U.S. ports of embarkation, however.
"Passengers on ships embarking or disembarking at US ports need to be vaccinated with FDA approved vaccines," reads the statement on Norwegian Cruise Line's website. "Mixed Pfizer / Moderna double vaccine shots are not approved by the FDA.
"All Other Vessels will accept any U.S. Food and Drug Administration (FDA), European Medicines Agency (EMA), or World Health Organization (WHO) authorized single brand vaccination protocol. Or a mixed vaccination protocol of only AstraZeneca-SK Bio, Pfizer-BioNTech or Moderna combinations."
While dose mixing is common in countries like Canada and the UK, the U.S. FDA does not recognize vaccine mixing, and only recognizes vaccines made by Pfizer, Moderna and Johnson & Johnson.
Sources have told Cruise Critic on background that the new changes are being mandated by the U.S. Centers for Disease Control and Prevention for voyages leaving U.S. ports of call as part of the CDC's Conditional Sail Order, though not every line has announced this policy.
Eagle-eyed Cruise Critic readers spotted the changes.
"Holland America Line just updated their FAQ to say that those who get mixed vaccines (I got AZ first and Moderna second as recommended by Canadian gov't) will not be considered fully vaccinated," writes mathgirl314 ."No longer able to go on our Aug 7 cruise to Alaska."
"WOW," writes Kazu in response. "That’s going to eliminate a lot people who are vaccinated.
Others wondered what to do with their government documentation that doesn't show what their first vaccine brand was.
"What do they need as proof?" writes xcell. "I have friends who had mixed dose, and their vaccine confirmation print out says that they have received Moderna/Pfzier as their second dose. They are fully vaccinated but it doesn't mention what their first dose was (i.e. Astra)."
Many Cruise Critic members discovered the changes only by accident.
"I was about to book a summer sailing to Alaska for a client and am so glad I read every piece of fine print," writes ceilidh1. "Princess are not accepting those with Astra Zeneca followed by Moderna/Pfizer. This could potentially impact MANY Canadians who were "urged" to accept whatever vaccine was offered."
In many cases, residents were not given the choice of which vaccine they could take, and were encouraged to take the first one available to them.
It was not immediately apparent where the mandate for these changes came from. Cruise Critic has reached out to several cruise lines for comment and will update this article with more information when it becomes available.