At last report, Norwegian Cruise Line Holdings (NCLH 0.66%) was the only major publicly traded cruise line stock in the U.S. to require that "all guests and crew must be fully vaccinated [against COVID-19] at least 2 weeks prior to departure, in order to board." (Once the company is able to cruise at all, that is).  

Cruise rival Carnival Corporation (CCL -0.42%), meanwhile, is reportedly still considering the issue -- but apparently leaning away from requiring vaccinations.

And Royal Caribbean (RCL 1.23%)?

Collage showing a cruise ship, a man in a face mask and a microbe

Image source: Getty Images.

Up until last week, I would have said Royal Caribbean was taking a middle road, requiring vaccinations for passengers aged 18 and up -- but now it seems they're leaning more in Norwegian's direction.

In a weekend update to the company's FAQ page, dropping the lower age limit on required vaccinations, Royal Caribbean announced that "for sailings departing on or before August 1, all Royal Caribbean guests age 16 and older must complete all doses of their COVID-19 vaccine at least 14 days before their sailing."

Furthermore, "for sailings departing after August 1, the age requirement for vaccination will change from 16 to 12 years of age."  

The change appears to be in response to the U.S. Centers for Disease Control decision, announced May 12, "that endorsed the safety and effectiveness of the Pfizer (PFE 2.40%) -BioNTech (BNTX 0.74%) COVID-19 vaccine and its use in 12- through 15-year-old adolescents."

No similar provision has been made for allowing minors to receive Moderna's (MRNA -0.58%) anti-COVID concoction. But the fact that there's at least one widely available FDA vaccine on the market conditionally approved for 12-year-olds may have convinced Royal Caribbean to mandate vaccination for this age bracket as well, to assure all future passengers that the company is doing all it can to minimize transmission risks for everyone aboard.