April 16 was a big day for Moderna, a Massachusetts biotech company on the verge of becoming a front-runner in the U.S. government’s race for a coronavirus vaccine. It had received roughly half a billion...

Even though 11.4 million doses of the approved Pfizer and Moderna COVID-19 vaccines had been distributed across the United States by Monday morning, just 2.1 million had made it into the arms of high-risk...