FDA granted emergency use authorization to Johnson & Johnson’s one-shot COVID-19 vaccine Saturday (Feb. 27), just one day after the agency’s panel of vaccine advisers unanimously endorsed the shot . J&J’s product, which is authorized for use in people who are 18 years of age or older, is the third coronavirus vaccine cleared for emergency use by FDA. It’s expected that the authorization will take the vaccine supply in the United States up to about 700 million doses, which would...