The U.S. FDA has expanded the emergency use authorization (EUA) of a booster dose of the Pfizer–BioNTech COVID-19 Vaccine to include individuals 18 years and older. The booster dose is to be administered at least six months after completion of the primary series, and is the same dosage strength as the doses in the primary series.    In October, the companies announced positive results from a trial showing that a booster dose administered to those who previously received the Pfizer-BioNTe...