A vaccine developed by Pfizer Inc. and BioNTech SEprotects most people from Covid-19, according to a study whose early findings sent stock prices surging and were hailed by the top U.S. infectious-disease specialist as “extraordinary.” The shot prevented more than 90% of symptomatic infections in the trial of tens of thousands of volunteers, the most encouraging scientific advance so far in the battle against the coronavirus. Pfizer shares closed 7,69% higher while BioNTech American depositary receipts surged 13,91%.