The company said on Monday that a booster shot of the vaccine raises the level of anti-Omicron antibodies.
The news arrives as Omicron rapidly advances across the world, and most coronaviruses vaccines seem unable to stave off infection from the highly contagious variant.
Moderna said that the booster dose of 50 micrograms, half the dose given for primary immunization, increased the level of antibodies by 37 times. Moderna said that a full dose of 100 micrograms was even more powerful than the pre-boost levels.
Side effects were similar to those seen after the two-dose primary series. The authorized 50-microgram dose had slightly more frequent adverse reactions than the 100 micrograms dose.
The results are based on tests that do not capture the full range of the immune response. The vaccine is expected to prevent severe illness in the vast majority of people.
The data has not been published or reviewed by experts. The data that would be posted online was being prepared by Moderna.
Pfizer and BioNTech announced earlier this month that a booster shot of their vaccine increased the level of antibodies against Omicron.
The vaccine was tested in 20 people. All the individuals had low levels of antibodies that can prevent Omicron infections before boosting. After receiving a third shot, the 50 microgram and 100 microgram doses of the current vaccine both increased.
The company tested booster shots that incorporate the same genes found in Omicron. There are between 300 and 600 people in the continuing trials. Moderna said that the 50-microgram and 100 microgram doses of the multivalent boosters increased the levels of the antibody.
Moderna said the company will focus on extra shots of the original vaccine given how quickly Omicron is moving. It plans to test a booster shot that is specific to the Omicron variant early next year.
Moderna will continue to advance an Omicron-specific booster candidate into clinical testing in case it becomes necessary in the future.
