On July 13, 2003, the last sars patient walked out of Tan Tock Seng and it was over. Some people loosely say that SARS “burned out,” having killed only seven hundred and seventy-four people worldwide. It didn't burn out. As Ali Khan told me, it was stopped.

“What are you most concerned about now?” I asked Brenda Ang, at Tan Tock Seng, six years later [in 2009].

She laughed in frustration. “Complacency,” she said. “And apathy.” Mundane but crucial infection-control measures—the assiduous hand washing and wiping of doorknobs with alcohol—can lapse after a crisis. “People become complacent. They think there is no new bugs around.” And larger lessons, beyond the outbreak locale, beyond Singapore? “There's no point just protecting your own turf,” she said. “Infectious diseases are so globalized.”

Ali Khan later told me the same thing: “A disease anywhere is a disease everywhere.”

— from “The Warnings: Why we should have known to prepare for COVID-19,” by David Quammen, in the May 11 New Yorker, about the successful battles to contain SARS and MERS. It's where I also learned a new word: zoonotic. We should all know this word.