The Centers for Disease Control and Prevention has bumped its warning level for cruise ship travel to the highest level as the U.S. breaks its daily COVID case record. Regardless of vaccination status, the CDC has urged travelers to skip cruises, especially since the potent Omicron spreads quickly in close quarters. “Today, CDC increased the Cruise Travel Health Notice (THN) to a Level 4, recommending people avoid cruise travel regardless of vaccination status,” the CDC said in a statement.

Per CNBC, the alert comes as nearly 5,000 onboard cases have been confirmed just within the last two weeks; the CDC has also reported that it’s monitoring as many as a dozen ships with outbreaks. For those who choose to cruise, the CDC has advised travelers to be fully vaccinated and boosted if possible. Travelers should also wear face masks in all communal quarters, and get tested, regardless of symptoms, both before and after travel.