Crystal is extending the need for all passengers and crew to be vaccinated requirement into 2022 for ocean ships Crystal Serenity and Crystal Symphony and expedition yacht Crystal Endeavor.
Crystal River Cruises will also require 100% passenger and crew vaccination into 2022.
The company said it will assess whether a booster shot for passengers and crew across the full fleet will be required once more information is available.
Crystal was the first major cruise line to require a Covid-19 vaccine in 2021 and now claims to be the first through into 2022.
The luxury line will require passengers aged 12 and above to be double jabbed at least 14 days prior to sailing.
They will need to provide documented proof of vaccination at the time of check-in before boarding.
All officers and crew across the Crystal fleet are fully vaccinated at least 14 days prior to service as a requirement of their employment.
President Jack Anderson said: “Protecting the health and safety of our guests and crew is paramount to everything we do and extending our vaccination requirements through 2022 is the next important step to continue to safeguard the health and wellness of our Crystal family.
“Our guests have overwhelmingly told us that vaccinations are critical for them to feel comfortable travelling and announcing this extension now will give them the information and reassurance they require as they look to plan future voyages with us.”