The triple Fates and unforgetting Furies


The U.K.’s B.1.1.7 variant has spread to more than eighty countries and has been doubling every ten days in the U.S., where it is expected to soon become the dominant variant. […] new evidence also suggests that people infected with it have higher viral loads and remain infectious longer, which could have implications for quarantine guidelines. […]

“The fact that different variants have independently hit on the same mutations suggests we’re already seeing the limits of where the virus can go,” McLellan told me. “It has a finite number of options.”

Over time, SARS-CoV-2 is likely to become less lethal, not more. When people are exposed to a virus, they often develop “cross-reactive” immunity that protects them against future infection, not just for that virus, but also for related strains; with time, the virus also exhausts the mutational possibilities that might allow it to infect cells while eluding the immune system’s memory. “This is what we think happened to viruses that cause the common cold,” McLellan said. “It probably caused a major illness in the past. Then it evolved to a place where it’s less deadly. But, of course, it’s still with us.” It’s possible that a coronavirus that now causes the common cold, OC43, was responsible for the “Russian flu” of 1889, which killed a million people. But OC43, like other coronaviruses, became less dangerous with time. Today, most of us are exposed to OC43 and other endemic coronaviruses as children, and we experience only mild symptoms. For SARS-CoV-2, such a future could be years or decades away.

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