(CNN) — Health officials in the United States have eased their stance on the safety of cruise travel for vaccinated passengers, lowering the travel alert level just over a week before the first cruise in more than 15 months is scheduled to set sail from a US port.
The US Centers for Disease Control and Prevention on Wednesday lowered its health notice on cruise travel from Level 4, which recommends avoiding all travel, to Level 3, which encourages travelers to get fully vaccinated before traveling.
The agency still advises that all unvaccinated travelers avoid travel on cruise ships.
"Since the virus spreads more easily between people in close quarters aboard ships, the chance of getting COVID-19 on cruise ships is high. It is especially important that people who are not fully vaccinated with an increased risk of severe illness avoid travel on cruise ships, including river cruises," the CDC says in its updated advisory.
It also advises that people who decide to go on a cruise should get tested one to three days before their trip and three to five days after. People who are not fully vaccinated should also self-quarantine for seven days after travel, even if they test negative. Those who do not get tested should self-quarantine for 10 days after travel.
Linsey Marr, a professor of civil and environmental engineering at Virginia Tech, says that the CDC easing this travel warning reflects the country's current situation.
"I think they can do that because enough people have been vaccinated, and cases are low enough right now that that lowers the overall risk," she told CNN.
However, Marr, who also studies the airborne transmission of Covid-19, gave an emphatic "no" when asked whether she'd recommend unvaccinated people go on cruises right now.
The CDC's lowered warning level comes as the industry prepares to restart in the United States. The first sailing from a US port is scheduled to depart on June 26 from Fort Lauderdale, Florida, on Celebrity Cruises' Celebrity Edge.
Vaccination is a hot topic for the industry, which is working to meet requirements outlined by the CDC's Conditional Sailing Order. Each ship must either perform a trial cruise with volunteer passengers to test safety protocols in advance of welcoming paying passengers or sail with 95% of passengers and crew who are vaccinated.
Vaccine requirements by businesses are banned in Florida, Texas and Alabama, where many cruise lines operate, yet several lines have already announced plans to resume operations this summer with vaccines required for most passengers.
Celebrity's posted policy says that all guests age 16 and older must be fully vaccinated, with the age requirement dropping to 12 on August 1.
It remains unclear how this and other cruise lines' policies will work with the vaccine requirement bans. The state of Florida has also sued the CDC over its requirements for the industry and that lawsuit has not yet been resolved.