The companies said there would be three trials examining different regimens of the current Pfizer-BioNTech vaccine for an omicron-based vaccine.
The first cohort received two doses of the Pfizer-BioNTech vaccine 90-180 days before enrollment and will receive one or two doses of the omicron-based vaccine.
In the second, participants received three doses of the Pfizer-BioNTech vaccine during the same timeframe and will receive one dose of the same vaccine or the omicron-based vaccine.
Lastly, the third trial participants will get three doses of the omicron-based vaccine.
"While current research and real-world data show that boosters continue to provide a high level of protection against severe disease and hospitalization with omicron, 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," Kathrin Jansen, Pfizer's head of vaccine research and development, said in a statement.
BioNTech CEO Ugur Sahin added that "emerging data indicate vaccine-induced protection against infection and mild to moderate disease wanes more rapidly than was observed with prior strains."
Pfizer CEO Albert Bourla – who tweeted about the Tuesday news – has previously said an omicron-specific vaccine would be ready by March.
"We already have begun work on a DNA template tailored to the sequence of omicron, a critical step in the process of advancing a variant version of our vaccine if in fact we find one is needed," a Pfizer spokesperson told FOX Business earlier this month. "[We are] also manufacturing the variant vaccine at risk, as we did for beta and delta before."
Pfizer and BioNTech expect to produce 4 billion doses of the COVID-19 vaccine in 2022, with that capacity not predicted to change if an adapted vaccine is required.
Data from the Centers for Disease Control and Prevention (CDC) shows that more than 313 million doses of the Pfizer-BioNTech have been administered and that majority of those fully vaccinated and boosted have been given the Pfizer-BioNTech vaccine.