(Reuters) — Royal Caribbean Group said on Wednesday it would delay the inaugural sailing of its Odyssey of the Seas cruise liner by nearly a month after eight crew members tested positive for COVID-19.

The news comes a week after two people tested positive for the virus on one of its Celebrity cruises, where the infected travelers were quarantined.

Odyssey of the Seas, which was scheduled to sail through Southern and Western Caribbean from Fort Lauderdale, will now sail on July 31 instead of July 3. A simulation cruise, originally scheduled for late June, will also be rescheduled.

Six of the eight people who tested positive were asymptomatic and two had mild symptoms, Michael Bayley, chief executive of Royal Caribbean International, said in a Facebook post.

The positive cases were identified after the crew were inoculated but before the vaccine became fully effective, the company said. All 1,400 crew members on board Odyssey were vaccinated on June 4 and will be considered fully vaccinated on June 18, it added.

Cruise companies were one of the worst hit during the pandemic as travel restrictions led to canceled trips and huge losses. They have been restarting their operations slowly and are preparing to sail from U.S. ports this summer.

As part of the U.S. Centers for Disease Control and Prevention’s (CDC) orders to restart trips, cruise companies require a majority of the passengers and crew to be vaccinated.

Reporting by Nivedita Balu in Bengaluru; Editing by Anil D’Silva © 2021 Thomson Reuters.