Nearly 20 percent of the U.S. population is fully vaccinated. Many countries may not hit that target this year.

In the United States, the good vaccine news keeps coming. For much of the world, things look bleak.

As of Thursday, just short of 20 percent of the U.S. population was fully vaccinated, giving some 66 million people a strong measure of protection against a disease that has already killed more than 500,000 Americans.

By contrast, Covax — a World Health Organization-backed push for equitable distribution — aims to secure enough doses to cover up to 20 percent of the people in participating countries by the end of 2021, but it may not meet that relatively modest goal, experts warn. Continue reading.