Biden Poised to Unleash Boosters Amid First-Shot Shortage Abroad

President Joe Biden is set to unveil a plan to give more Americans coronavirus vaccine booster shots to head off the delta variant, a move that is stoking criticism that the U.S. is hoarding doses while poorer nations continue to languish under the pandemic.

Under Biden’s plan, which he’s set to discuss in a speech Wednesday about the broader Covid-19 response, high-risk groups including health-care workers and the elderly may be able to get a third dose of Pfizer Inc. and Moderna Inc. vaccines as soon as September, or eight months after they received their second shot.

The Food and ...