Cruise major Royal Caribbean Group is putting its best face on disruption from the Covid-19 Omicron variant, saying the virus is producing milder symptoms and causing fewer cancelled bookings than the earlier Delta version.

The Miami company said the Omicron spike has so far resulted in only 16 destination calls out of 331 to be modified or cancelled. It added that bookings in the year's second half "continue to be booked within historical ranges, at higher prices with and without future cruise credits, with strong demand from the critical US market".

Royal Caribbean shares gained more than 1% on Thursday morning on light holiday-week volume following the company's "business update".

The operator said its own experience with Omicron had been consistent with other findings, showing the variant to be more transmissible but substantially milder than previous coronavirus forms.

Not a single passenger afflicted by Omicron has needed to be hospitalised, the company said.

Richard Fain, chairman and chief executive of Royal Caribbean Cruise Holdings, said: "Omicron is having a big short-term impact on everyone, but many observers see this as a major step towards Covid-19 becoming endemic rather than epidemic."

Royal Caribbean International's 3,114-berth cruiseship Adventure of the Seas (built 2001) sets sail from Nassau, Bahamas, in June 2021. Photo: Royal Caribbean Group

Since it resumed operations in June 2021, the operator has seen 1,745 passengers from 1.1m test positive, a rate of about 0.02%. Only 41 have required hospitalisation, but none from Omicron.

"Our case count has spiked, but the level of severity is significantly milder," said Dr Calvin Johnson, chief medical officer.

As TradeWinds has reported, accounts of outbreaks on more than 90 ships among the "big three" cruise majors — Royal Caribbean, Carnival Corp and Norwegian Cruise Line — have put the brakes on what had been rising share prices.

Royal Caribbean is still well off its recent shares high of $98.05 reached in early November, despite its climb above $79 on Thursday.

"Following a very strong cyber weekend, the company experienced a decline in bookings and increased cancellations for near-term sailings but to a lesser degree than that experienced with the Delta variant," Royal Caribbean said in the update.

"We are constantly learning and adjusting as Omicron appears to be ushering in a new phase in the fight against Covid-19," Fain said.

"We expect these factors to have a negative impact in the short term but are optimistic they will lead us to a more pervasive but less severe health environment.

"Taken together, this should enable us to produce a strong transitional year in 2022 and a very strong 2023."