Covid-19 vaccines have reached consumers in record time—vaccine development can take 10 to 15 years, but the U.S. Food and Drug Administration has granted emergency authorization to vaccines made by Pfizer-BioNTech and Moderna in less than a year.

Covid-19 vaccines have reached consumers in record time—vaccine development can take 10 to 15 years, but the U.S. Food and Drug Administration has granted emergency authorization to vaccines made by Pfizer-BioNTech...