Norwegian Cruise Line has announced that it’s extending its mandatory vaccination protocols required for all guests and crew for all sailings through Dec. 31, 2021.

According to a press statement, this decision was based under the guidance of globally recognized public health experts and “to prioritize the health and safety of our guests, crew and the communities we visit.”

Guests who are not old enough to be vaccinated will not be allowed on these sailings, Norwegian said. It added that it eagerly awaits an expansion of the age criteria for vaccinations by the U.S. Food and Drug Administration so that it can once again welcome the younger guests onboard.

Norwegian added that it will continue to refine its health and safety protocols with its public health experts as science, technology and knowledge of COVID-19 evolve.

“Under the guidance of globally recognized public health experts and to prioritize the health and safety of our guests, crew and the communities we visit, we have decided to extend guest vaccination requirements for all sailings through Dec. 31, 2021. Guests who are not old enough to be vaccinated will not be allowed on these sailings. However, we eagerly await an expansion of the age criteria for vaccinations by the U.S. Food and Drug Administration so we can once again welcome these guests back onboard,” said a spokesperson for Norwegian.

“We will continue to evaluate and modify our health and safety protocols with our team of scientific and public health experts as science and technology evolve … We thank our guests for their understanding and support as we address the challenges posed by COVID-19 to deliver a safe vacation experience,” they added.