A vaccine developed by Pfizer Inc. and BioNTech SE protects 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. While the results are preliminary, they may pave the way for the companies to seek an emergency-use authorization if further research shows the vaccine is also safe.