President Joe Biden said Tuesday that the US expects to take delivery of enough coronavirus vaccines for all adult Americans by the end of May, two months earlier than anticipated. The announcement comes as the White House looks to speed the production of the single-dose Johnson & Johnson vaccine and accelerate the nation's plans to reach "herd immunity". Johnson & Johnson has promised to deliver 100 million doses by the end of June. The Biden administration has told governors to prepare for their supplies of vaccine to continue to climb over the coming weeks. Additional doses are also heading toward a federally backed program to administer doses in more accessible retail pharmacies.