Pfizer and BioNTech have begun a clinical trial to evaluate an omicron-specific vaccine for COVID-19, the pharmaceutical companies announced Tuesday, according to NPR.

The study will include as many as 1,420 participants divided into three groups.

One group includes people who have already received two doses of the current Pfizer-BioNTech vaccine and will also receive the omicron vaccine. A second includes those with three doses of the current Pfizer vaccine who will also get the omicron vaccine. The third group includes unvaccinated people who will receive three shots of the omicron vaccine.

The Food and Drug Administration has authorized the current Pfizer-BioNTech COVID-19 vaccine for emergency use in people ages 5 and older. The Moderna and Johnson & Johnson vaccines are authorized for adults.

Though people who are vaccinated and boosted appear to be better protected against severe disease and hospitalization from omicron, the highly contagious variant has still led to breakthrough cases and a surge in overall infections around the world.

“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 U. Jansen, Pfizer’s senior vice president and head of vaccine research and development, said in a statement.