Pfizer Inc. said Wednesday that a third shot of its coronavirus vaccine could offer sufficient protection against the new Omicron variant, while the two-dose regimen may be less effective, citing the results of an initial laboratory study.

The U.S. pharmaceutical giant and its German partner BioNTech SE also said they started developing an Omicron-specific COVID-19 vaccine in late November and believe they can deliver it in March next year if needed.

Supplied photo shows a tray of Pfizer Inc.'s COVID-19 vaccines. (Photo courtesy of Pfizer Inc.)(Kyodo)

According to preliminary laboratory studies, a booster shot of the current COVID-19 vaccine can increase by 25-fold the antibodies that would help fight off Omicron, providing a similar high level of protection as observed from the two doses before the emergence of the new variant.

The research also showed that a two-dose course of the vaccine may not be sufficient to protect against infection with Omicron. But vaccinated individuals may still be protected against severe forms of the disease, the companies added.

"It's clear from these preliminary data that protection is improved with a third dose of our vaccine," said Albert Bourla, chairman and chief executive officer of Pfizer.

"Ensuring as many people as possible are fully vaccinated with the first two-dose series and a booster remains the best course of action to prevent the spread of COVID-19," he said.

The two companies, meanwhile, said their vaccine production capacity is not expected to change from the previously announced 4 billion doses in 2022 even if an updated vaccine is required.