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Opinion
Justin Fox

Most Important Covid-19 Policy? Pick One and Stick to It

It's one thing Sweden may have gotten right, as other places are discovering.

A woman wears a face mask as she waits at a bus stop with an information sign asking people to keep social distance on June 26, 2020 in Stockholm, Sweden.

A woman wears a face mask as she waits at a bus stop with an information sign asking people to keep social distance on June 26, 2020 in Stockholm, Sweden.

Photographer: STINA STJERNKVIST/AFP/Getty Images

Early last December, when epidemiologist Adam Kucharski of the London School of Hygiene and Tropical Medicine signed off on the final manuscript of “The Rules of Contagion: Why Things Spread — and Why They Stop,” a dangerous new virus was beginning to spread undetected in Wuhan, China. By the time the book was published in the U.K. on February 13, the new plague had just gotten a name — SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), for the virus itself and Covid-19 for the disease it causes — and begun its rapid spread in the U.S. and Europe. You know what happened after that.

But the fact that you know what happened and Kucharski didn’t (for the U.S. edition, which came out in July, he was at least able to squeeze in a few brief references to Covid-19) doesn’t detract at all from his book. A mathematician by training, Kucharski adeptly explains the basics of how infections spread and fizzle out, and how the insights epidemiologists began to develop in the early 20th century are now being used to study phenomena from financial crises to viral tweets.