The U.S. Centers for Disease Control and Prevention (CDC) on Wednesday removed its COVID-19 notice against cruise travel, around two years after introducing a warning scale showing the level of coronavirus transmission risk on cruise ships.

The move offers a shot of hope to major U.S. cruise operators such as Carnival Corp, Royal Caribbean Group and Norwegian Cruise Line Holdings Ltd that have struggled to bring in revenue since the pandemic started.

Cruise operators had also said the health agency was discriminating against the industry, when hotels and airlines could operate with limited or no restrictions.

"While cruising will always pose some risk of COVID-19 transmission, travelers will make their own risk assessment when choosing to travel on a cruise ship, much like they do in all other travel settings," the CDC said in a statement.

The guidelines for traveling on cruise ships on the health agency's page no longer shows https://www.cdc.gov/coronavirus/2019-ncov/travelers/cruise-travel-during-covid19.html a scale for its warning. Instead, it now only says guests should make sure they are up to date with their COVID-19 vaccines before boarding the ships.