Covid is more mysterious than we often admit.

Not in control

Consider these Covid-19 mysteries:
• In India — where the Delta variant was first identified and caused a huge outbreak — cases have plunged over the past two months. A similar drop may now be underway in Britain. There is no clear explanation for these declines.
• In the U.S., cases started falling rapidly in early January. The decline began before vaccination was widespread and did not follow any evident changes in Americans’ Covid attitudes.
• In March and April, the Alpha variant helped cause a sharp rise in cases in the upper Midwest and Canada. That outbreak seemed poised to spread to the rest of North America — but did not.
• This spring, caseloads were not consistently higher in parts of the U.S. that had relaxed masking and social distancing measures (like Florida and Texas) than in regions that remained vigilant.
• Large parts of Africa and Asia still have not experienced outbreaks as big as those in Europe, North America and South America.

How do we solve these mysteries? Michael Osterholm, who runs an infectious disease research center at the University of Minnesota, suggests that people keep in mind one overriding idea: humility.

“We’ve ascribed far too much human authority over the virus,” he told me.

‘Much, much milder’
Over the course of this pandemic, I have found one of my early assumptions especially hard to shake. It’s one that many other people seem to share — namely, that a virus always keeps spreading, eventually infecting almost the entire population, unless human beings take actions to stop it. And this idea does have crucial aspects of truth. Social distancing and especially vaccination can save lives.

But much of the ebb and flow of a pandemic cannot be explained by changes in human behavior. That was true with influenza a century ago, and it is true with Covid now. An outbreak often fizzles mysteriously, like a forest fire that fails to jump from one patch of trees to another.
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