Pfizer COVID-19 vaccine
Pfizer COVID-19 vaccineKobi Richter/TPS

Pfizer and BioNTech have begun enrollment for a clinical trial to test the safety and immune response of their Omicron-specific COVID-19 vaccine in adults aged up to 55, the companies said in a statement quoted by AFP on Tuesday.

Pfizer’s head of vaccine research, Kathrin Jansen, said in a statement that while current data showed that boosters against the original COVID strain continued to protect against severe outcomes with Omicron, the company was acting out of caution.

"We recognize the need to be prepared in the event this protection wanes over time and to potentially help address Omicron and new variants in the future," she said.

Ugur Sahin, CEO of the German biotech company BioNTech, added that the protection of the original vaccine against mild and moderate Covid appeared to wane more rapidly against Omicron.

"This study is part of our science-based approach to develop a variant-based vaccine that achieves a similar level of protection against Omicron as it did with earlier variants but longer duration of protection."

The trial will involve 1,420 people aged 18-55.

Pfizer CEO Albert Bourla said earlier this month that the vaccine that targets the Omicron variant of COVID-19 will be ready in March, and the company has already begun manufacturing the doses.

“This vaccine will be ready in March. We [are] already starting manufacturing some of these quantities at risk,” he told CNBC.

Bourla said the vaccine will also target the other variants that are circulating. He said it is still not clear whether or not an Omicron vaccine is needed or how it would be used, but Pfizer will have some doses ready since some countries want it ready as soon as possible.

Bourla said in November that three doses of the Pfizer vaccine would remain effective even against the Omicron variant of the coronavirus, but added that a new vaccine specifically made to combat the new strain could be ready in 100 days.