Only a few of the world’s 82 poorest countries — including Bangladesh, Bhutan, Cambodia and Nepal — have reached the 70 percent vaccination threshold. Many are under 20 percent, according to data compiled from government sources by the Our World in Data project at the University of Oxford.

By comparison, about two-thirds of the world’s richest countries have reached 70 percent. (The United States is at 66 percent.)

The consequences of giving up on achieving high vaccination coverage worldwide could prove severe. Public health experts say that abandoning the global effort could lead to the emergence of dangerous new variants that would threaten the world’s precarious efforts to live with the virus.