For instance, we have new evidence suggesting that multiple sclerosis is linked to the extremely common Epstein-Barr virus; estimates of M.S. cases in the United States range from 400,000 to just under a million. Likewise, chronic fatigue syndrome may well be touched off by viral infections; estimates of its victims range as high as 2.5 million. Start tallying up the myriad other chronic conditions that might have some infectious root, and you could make a case for Emanuel’s level of caution just based on pre-Covid threats.

But that’s not how human civilization has traditionally dealt with chronic dangers. We take unusual precautions during unusually deadly outbreaks, but where dangers are persistent, we look for ways to treat and cure while otherwise trying to live our lives as normally as possible. Certainly we don’t look back at images of an 18th-century court or coffeehouse, when the risks from infectious disease were greater than anything we know, and say: “Why aren’t those people wearing masks? Why did they ever leave the house?”

Chronic illness is a great scourge, which long Covid has helped bring into the light, and it cries out for better diagnosis and better treatment. But doing the math and knowing the danger won’t keep me from showing my face on planes and in restaurants or my kids from walking — carefully, I hope — in Connecticut’s state parks.