WASHINGTON (CBS News) — A panel of the Food and Drug Administration’s vaccine advisers voted unanimously Friday in favor of an emergency use authorization for a third dose of Pfizer’s COVID-19 vaccine, six months after some Americans completed their first two doses. The vote follows a day-long meeting discussing evidence around potentially waning immunity from the company’s first two shots in the face of the highly contagious Delta variant.

The panel had initially rejected by a majority vote over Pfizer’s request for full approval of a booster. A new framing of the question tailored the authorization to “individuals 65 years of age and older, and individuals at high risk of severe COVID-19.”

While the panel’s vote is not binding, FDA officials have cited the public discussion of the Vaccines and Related Biological Products Advisory Committee as a key step in deciding whether to approve booster shots.