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.