Moderna announced that preliminary data suggests their half-dose booster shot increased antibody levels against Omicron. This is in comparison with the levels seen when a fully vaccinated person does not receive a booster. CEO Stéphane Bancel called the data "reassuring” in a statement from the company.

"The dramatic increase in COVID-19 cases from the Omicron variant is concerning to all. However, these data showing that the currently authorized Moderna COVID-19 booster can boost neutralizing antibody levels 37-fold higher than pre-boost levels are reassuring," Bancel said in the announcement.

"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."

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said during a virtual White House briefing on Wednesday that Covid-19 booster shots helps to improve protection against the Omicron coronavirus variant. There was no need for a variant-specific booster dose currently.

Fauci also added that anyone who is unvaccinated should get vaccinated. In the case of Omicron particularly, a person who is fully vaccinated should get a booster shot.

Moderna administers a 50-microgram dose as a booster dose. The company announcement that this booster dose increased antibody levels 37-fold and a 100-microgram booster dose increased antibody levels 83-fold compared with levels seen before a booster.