At the same time, Carnival implemented a fleetwide mask policy requiring all passengers to wear masks in some indoor areas.
The company didn't immediately reveal how many positive cases had been detected on Vista, which departed from Galveston Texas on July 31 and is scheduled to sail back on Saturday, August 7. Call ports include (03 Aug 08:00 - 18:00) Roatan Island, Mahogany Bay-Coxen Hole, Honduras; (04 Aug 08:00 - 17:00) Belize City; (05 Aug 08:00 - 16:00) Cozumel, Quintana Roo Mexico, Riviera Maya; (07 Aug 08:00) arriving in Galveston, Texas.
CCL said the positive guests were in isolation. Their close contacts had been identified and tested.
"Our pre-established protocols of vaccinated guests and crew, testing, enhanced medical capabilities and contact tracing anticipated the potential for positive cases, and they are designed to adapt to various scenarios."
The new policy requiring all guests, even the vaccinated, to wear masks in certain indoor areas was due to go into effect for voyages departing on/after August 7, but the positive COVID cases prompted an immediate start aboard Vista Wednesday evening.
The cruise will go on as planned, the line said.
In addition to the new mask rule, CCL is adding a pre-cruise testing requirement for all vaccinated passengers. Fully vaccinated guests must have a negative COVID test result (PCR/antigen) taken within 3 days of departure.
This rule goes into effect on August 14. Both new requirements are expected to be in place through October 31.
For more Carnival Vista accidents and incidents see the ship's CruiseMinus page.