By David Leonhardt
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.