FDA authorizes Johnson & Johnson’s single-shot coronavirus vaccine, adding to the nation’s arsenal against the pandemic

The Food and Drug Administration late Saturday granted emergency use authorization to Johnson & Johnson’s single-dose coronavirus vaccine, providing the United States with a long-anticipated tool that adds firepower and flexibility to the nation’s accelerating inoculation effort — but also presents new challenges.

Health authorities now have three effective vaccines, a singular scientific achievement that few would have predicted a year ago, when a pandemic emerged that has killed 2.5 million people worldwide, including more than 500,000 in the United States. It comes at a particularly fraught time, as Americans are whipsawed by encouraging developments, including sharp declines in nursing home deaths, and concerning news such as the emergence of potentially menacing variants.