At Cheyenne Regional Medical Center in Wyoming, health workers didn't need genomic sequencing to tell them the highly contagious Delta variant had arrived.

Younger patients started coming in about two months ago with symptoms of Covid-19. Many progressed from mild illness to respiratory distress more quickly than patients treated earlier in the pandemic, said Sodienye Tetenta, a critical-care physician at the hospital. Nearly all were unvaccinated.

"We could see that this was not the Covid of last year," Dr. Tetenta said.

SANTA CLARA COVID-19 DEATH TOLL DROPS BY 22% AFTER REVIEW

The Delta variant is hardening a divide between people who are fully vaccinated against Covid-19 and those who aren't, prompting hospitals to brace for new case surges and health authorities to redouble vaccination efforts. Now the most common strain in the U.S., Delta is spreading as public life resumes at restaurants, sporting events and other public settings across the country.

Infections from the Delta strain contributed to a 10% rise in daily Covid-19 cases to around 12,600 late last month, the Centers for Disease Control and Prevention said on Thursday. That is still a 95% drop from peak levels in the U.S. in January. And hospital admissions tied to Covid-19 dropped 1% from a week earlier, the CDC said. Vaccines available in the U.S. protect against the Delta variant, studies have shown, and cases of breakthrough infection in the fully vaccinated appear to rarely result in severe illness.

To the unvaccinated, though, the Delta variant poses an elevated threat. It is some 50% more transmissible than the Alpha variant that had been the most common strain in the U.S. since March, and scientists believe Delta is associated with more severe disease. CDC Director Rochelle Walensky said on Thursday that preliminary data collected from a set of U.S. states over the past six months showed that 99.5% of people who died of Covid-19 were unvaccinated.

"It is clear that communities where people remain unvaccinated are communities that remain vulnerable," she said.

FULLY VACCINATED VETERAN HOSPITALIZED

Los Angeles County public-health officials urged all people last week to wear a mask indoors in public places, regardless of vaccination status because of the Delta variant. In Arkansas, 34.5% of the population is fully vaccinated, 13 percentage points below the national average, according to the CDC. The weekly rate of 110 new cases per 100,000 Arkansas residents is the highest in the country, according to CDC data.

Wyoming isn't far behind, with 85 new cases per 100,000 residents, CDC data showed. In Laramie County, which includes Cheyenne, the Delta variant is spreading in a population where 32% of people are fully vaccinated against Covid-19, compared with 47% of the U.S. population overall.

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"You have this sickening feeling that there are people who may not make it through because of wrong choices," said Dr. Tetenta of Cheyenne Regional.

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