WASHINGTON (AP) — Pfizer’s COVID-19 vaccine faces one final hurdle before an expected decision to greenlight the shot for use in millions of Americans. Food and Drug Administration advisers meet Thursday to scrutinize the company’s data for any red flags or oversights. The public review comes as U.K. regulators investigate two apparent cases of allergic reaction to the vaccine. Safety will be top of mind for the panel of medical experts, who will vote on whether to endorse the vaccine. They will also address unknowns about the vaccine’s effectiveness in certain groups. A final FDA decision and the first shots could follow within days.