A few cruise lines have announced new policies regarding which Covid-19 vaccines are acceptable, as well as prohibiting mixed vaccine regiments.
At least three cruise lines have announced new policies this week.
Norwegian Cruise Line has updated its policy to say their U.S. based vessels will not accept mixed vaccinations, such as Pfizer + Moderna or AstraZeneca + Pfizer, etc.
NCL will accept accept any U.S. Food and Drug Administration (FDA) and/or World Health Organization (WHO) authorized single brand vaccination protocol.
This includes J&J Janssen, Pfizer-BioNTech, Moderna, AstraZeneca/Oxford.
NCL's other ships not based in the U.S. 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.
Holland America Line & Princess Cruises also updated their policies to exclude mixed vaccinations.
The website for both Princess and HAL indicates guests who have had one single does of a vector vaccine and a single dose of a mRNA vaccine will not considered fully vaccinated, whereas guests who have had mixed vaccines from the same type of vaccine will be considered fully vaccinated.
"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., both are 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 also added verbiage addressing mixed vaccines to their website.
Carnival says Pfizer and Moderna can be mixed to complete a full vaccination series. All other vaccines in a 2-dose series are required to be of the same type.
UPDATE: Royal Caribbean has updated its policy to match other cruise lines.
The policy change among the cruise lines comes just days after the World Health Organization (WHO) warned of the trend of mixing vaccines as "dangerous".
WHO's chief scientist Soumya Swaminathan spoke about the issues with mixing vaccines earlier this week, "It's a little bit of a dangerous trend here."
"We're in a data-free, evidence-free zone here as far as mix-and-match. There is limited data on mix-and-match. It will be a chaotic situation in countries if citizens start deciding when and who will be taking a second, a third, and a fourth dose."
The U.S. Centers for Disease Control and Prevention (CDC) says on its website Covid-19 vaccines are not interchangeable.
"The safety and efficacy of a mixed-product series have not been evaluated. Both doses of the series should be completed with the same product."
While the CDC advises against mixing and matching, it does address those "exceptional situations" in which it's unclear whether someone had an initial dose of a Pfizer or Moderna mRNA vaccine, for example. In that case, "any available mRNA COVID-19 vaccine may be administered" to complete the series.