CNN  — 

Moderna said on Wednesday its bivalent Covid-19 vaccine booster that contained a vaccine targeting the Omicron variant showed a stronger immune response against the variant.

Bivalent boosters address two viral strains in the same vaccine. The updated booster contains Moderna’s original vaccine, and a vaccine candidate that targets the Omicron variant.

The vaccine was generally well-tolerated, the company said, with side effects similar to booster doses of the current vaccine.

The 50-microgram bivalent booster, called mRNA-1273.214, generated a stronger antibody response against Omicron than the original Moderna vaccine. Omicron subvariants are driving virtually all the new Covid-19 cases in the United States right now.

Stéphane Bancel, chief executive officer of Moderna, said in a news release “we anticipate more durable protection against variants of concern with mRNA-1273.214, making it our lead candidate for a Fall 2022 booster.”

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He said the company will submit its preliminary data and analysis to regulators so that the Omicron-containing bivalent booster will be available in late summer. The US Food and Drug Administration’s vaccine advisers are set to meet June 28 to discuss whether coronavirus vaccine compositions should be modified for fall 2022.

In April, Moderna announced its first bivalent Covid-19 booster shot candidate – which combined elements of the current vaccine with updates based on the Beta variant – induced higher antibody responses against all variants of concern, including Omicron, when compared to the company’s original Covid-19 booster shot.