The U.S. vaccine supply is poised to double in the coming weeks and months, according to an analysis by Bloomberg, allowing a broad expansion of doses administered across the country. Covid-19 vaccine manufacturers and U.S. officials have accelerated their production timelines, and Drew Armstrong reports that the spigots are about to open, providing hundreds of millions of doses just as pharmacies and mass-vaccination sites become more equipped to administer them.See omnystudio.com/listener for privacy information.