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Some Covid-19 hot spots in the U.S. are nearing the point at which delta-variant surges in other countries flamed out.

Delta waves in India and the U.K. have been marked by hyperspeed spikes in infections that eased dramatically after about two months. The first major U.S. Covid outbreaks of the delta era -- in Missouri and Arkansas -- started in earnest around the end of May.

The rest of the U.S. will be watching those states closely as infections spread. The cases are prompting authorities to reconsider masking and other public-health measures, but many state and local governments are doing so gingerly and only after outbreaks are well underway. In Florida’s Miami-Dade County, Mayor Daniella Levine Cava said Wednesday that she would require masks again at indoor county facilities such as libraries.


The tepid response is a sign of the complexities of dealing with a resurgence that’s unfolding at an alarming pace but killing far fewer people.

In the Ozarks, hospitals continue to see elevated levels of Covid-19 admissions. But an estimate of the effective reproduction number -- a measure of average new infections from one infected person -- suggests that those states’ waves may be peaking, as former Food and Drug Administration commissioner Scott Gottlieb said Thursday on Twitter. That number, known as Rt, indicates cases should fall if it’s below 1.

Gottlieb cited data from covidestim, a project with contributors from Yale School of Public Health and Harvard’s T.H. Chan School of Public Health.