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December 20, 2021

Moderna's COVID-19 booster shot protects against omicron variant, data shows

An omicron-specific dose is in the works in case it becomes necessary, the company says

Moderna's half-dose booster shot increases antibodies against the omicron coronavirus variant, the biotechnology company said Monday.

And the protection is even stronger when a larger booster dose is given.

Moderna's COVID-19 booster shot is currently available as a 50-microgram dose — half the dosage of each shot administered in the initial vaccine regimen. Preliminary data suggests that increases antibody levels 37-fold against omicron. 

A 100-microgram booster dose increases antibody levels 83-fold compared to levels measured before the booster.

Side effects of the half-dose booster are comparable to those caused by the primary two-dose series, the company said. But the 100-microgram booster was associated with more frequent adverse reactions.

Moderna CEO Stéphane Bancel said the data is "reassuring."

"To respond to this highly transmissible variant, Moderna will continue to rapidly advance an omicron-specific booster candidate into clinical testing in case it becomes necessary in the future," Bancel said. "We will also continue to generate and share data across our booster strategies with public health authorities to help them make evidence-based decisions on the best vaccination strategies against SARS-CoV-2."

The data has yet to be published or peer-reviewed, but the company said it is working on a manuscript that will be posted online.

Moderna also is testing a "multivalent" booster shot that offers protection against mutations found in multiple variants including beta, delta and omicron, according to the New York Times. While the clinical trials are ongoing, the company indicated this booster dose also increases antibody levels significantly.

Other vaccine manufacturers have said they are working on variant-specific booster shots as well.

About 32% of fully-vaccinated U.S. adults have received a booster dose so far, according to the U.S. Centers for Disease Control and Prevention. Health officials have been encouraging all eligible Americans to get booster doses as omicron infections spread across the country even among vaccinated people. 

None of the authorized vaccines are fully protective against the new variant, but they are still able to prevent severe illness is most people.

Pfizer and BioNTech also have released data showing a booster shot of their COVID-19 vaccine increases antibody levels against omicron.

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