Moderna vaccine
Moderna vaccineReuters

Moderna announced on Wednesday that the first participant has been dosed in the company's Phase 2 clinical trial of a COVID-19 vaccine booster shot that is specific to the Omicron variant.

"We are reassured by the antibody persistence against Omicron at six months after the currently authorized 50 μg booster of mRNA-1273. Nonetheless, given the long-term threat demonstrated by Omicron's immune escape, we are advancing our Omicron-specific variant vaccine booster candidate and we are pleased to begin this part of our Phase 2 study," CEO Stéphane Bancel said in a news release, according to CNN.

"We are also evaluating whether to include this Omicron-specific candidate in our multivalent booster program," he added.

Moderna will be enrolling two groups in its clinical trial: People who received two doses of its vaccine at least six months ago, and people who received two doses plus a booster shot at least three months ago.

The company said it expects to enroll approximately 300 participants into each arm of the trial, which will be conducted at up to 24 sites in the U.S.

Meanwhile, a study published Wednesday found that the Moderna COVID-19 booster shot remains durable against the Omicron variant, but the antibody protection wanes and is six times lower six months after getting boosted.

The study, published in the New England Journal of Medicine, also found that the neutralizing antibody levels declined against the Omicron variant much more rapidly than against the dominant strain of the virus that was circulating two years ago.

Wednesday’s announcement comes a day after Pfizer and BioNTech said they 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.

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.

The Pfizer CEO 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.