ATLANTA (WJW)– The Centers for Disease Control issued new guidance for cruise ships: Avoid them.

On Thursday, the CDC raised the COVID-19 Travel Health Notice level from 3 to 4, which is the highest, indicating a increase in cases on cruise ships following the identification of the omicron variant.

The national health agency urged people to avoid travel on a cruise ship, regardless of vaccination status.

“Even fully vaccinated travelers may be at risk for getting and spreading COVID-19 variants,” the CDC said on Thursday. “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.”

According to the recommendations, people should get tested 1 to 3 days before their trip and 3 to 5 days after. Those who are not full vaccinated should self-quarantine for 5 days after the cruise.