The Centers for Disease Control and Prevention does not plan to change the definition of what it means to be "fully vaccinated" right now that BioNTech SE BNTX, -6.54% and Pfizer Inc.'s PFE, -0.57% COVID-19 booster shots are available for a large group of the U.S. population. During a White House briefing on Friday, CDC director Rochelle Walensky said "we need to have more experience with our third shot and have more people eligible or recommended to receive it, before we change that definition." The Food and Drug Administration on Wednesday authorized a third booster dose of Pfizer's two-dose vaccine, making it the first vaccine to receive regulatory authorization for a booster. Moderna Inc.'s MRNA, -4.57% application for a booster shot for its two-dose vaccine is currently under review at the FDA.