The Centers for Disease Control and Prevention issued an alert on Thursday warning Americans to avoid traveling on cruise ships due to the rapid spread of COVID-19 and in light of recent outbreaks on cruise liners.

The CDC extended that warning even to fully vaccinated people. 

“The virus that causes COVID-19 spreads easily between people in close quarters on board ships, and the chance of getting COVID-19 on cruise ships is very high, even if you are fully vaccinated and have received a COVID-19 vaccine booster dose,” the CDC said in its alert.

The Omicron variant of the coronavirus has sent U.S. cases of COVID-19 to record levels, though the cases have