LOS ANGELES — Millions of people had started to shelter in place. The global economy was cratering. Coronavirus-panicked shoppers were clawing at each other over toilet paper. But apocalypse be darned. Ashley McCormick, a fashion publicist at Ragdoll PR in Los Angeles, had a product to promote. “Forget everything you’ve ever heard about latex,” her March 19 email to lifestyle journalists began. She was not referring to gloves. “Latex has become an inescapable fashion sensation, with designers creating unique and innovative looks for both on and off the runway,” Ms. McCormick wrote, citing...