In just a matter of weeks, two variants of the coronavirus have become so familiar that you can hear their inscrutable alphanumeric names regularly uttered on television news.

B.1.1.7, first identified in Britain, has demonstrated the power to spread far and fast. In South Africa, a mutant called B.1.351 can dodge human antibodies, blunting the effectiveness of some vaccines.

COACHELLA, Calif. — The sun-baked desert valley tucked behind the San Jacinto Mountains is best known for an annual music festival that draws 100,000 fans a day and a series of lush, oasis resort towns where well-heeled snowbirds go to golf, sunbathe and party. But just beyond the turquoise swimming pools of Palm Springs, more than 10,000 farmworkers harvest some of the country’s largest crops of date palms, vegetables and fruits.

EAST HARTFORD, Conn. — With the nation’s coronavirus vaccine supply expected to swell over the next few months, states and cities are rushing to open mass vaccination sites capable of injecting thousands of shots a day into the arms of Americans, an approach the Biden administration has seized on as crucial for reaching herd immunity in a nation of 330 million.