WASHINGTON, United States (AFP) — The US Food and Drug Administration (FDA) on Thursday expanded authorization of the Pfizer-BioNTech Covid booster to include 16- and 17-year-olds, amid growing concern over the Omicron variant’s ability to overcome immunity conferred by two shots. The FDA’s decision comes a day after the companies released the results of lab tests that showed three doses appeared effective against Omicron, while two doses were probably not enough to stop infection — […]