Moderna announced Monday that its booster provides protection against COVID-19 variant omicron. In its testing, Moderna found a 50-microgram dose resulted in a 37-fold increase of antibodies compared to vaccinated, unboosted individuals. 

A 100 µg dose, which is the same amount used in the first two vaccine doses, provided even more protection, increasing antibody levels 83-fold. But that increased immune response was paired with slightly worse side effects than with the smaller dose. 

Moderna’s data is preliminary and has not been reviewed, but CEO Stéphane Bancel said the results are “reassuring” all the same and touted the company’s work on a booster targeted specifically at omicron. “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. 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.”