Coronavirus cases and hospitalizations in the United States are at a six-month high, fueled by the rapid spread of the Delta variant across swathes of the country grappling with low vaccination rates.

Nationwide, COVID-19 cases have averaged 100,000 for three days in a row, up 35% over the past week, according to a Reuters tally of public health data. The surge of the disease was strongest in Louisiana, Florida and Arkansas.

Hospitalizations rose 40% and deaths, a lagging indicator, registered an 18% uptick in the past week with the most fatalities by population in Arkansas.

The intensifying spread of the pandemic has led to cancellation of some large high-profile events. One notable exception is an annual motorcycle rally in South Dakota which has been proceeding as planned.

Florida set records for hospitalizations for eight days in a row, according to the analysis. In that state, most students are due back in the classroom this week as some school districts debate whether to require masks for pupils.

The head of the nation's second-largest teachers' union on Sunday announced a shift in course by backing mandated vaccinations for U.S. teachers in an effort to protect students who are too young to be inoculated.

The number of children hospitalized with COVID-19 is rising across the country, a trend health experts attribute to the Delta variant being more likely to infect children than the original Alpha strain.

With the virus once again upending Americans' lives after a brief summer lull, the push to vaccinate those still reluctant has gained fresh momentum.

States including California, New York and Virginia have mandated vaccinations or weekly testing for state employees, as well as several cities.

The administration of President Joe Biden set new rules late last month requiring federal workers to provide proof of vaccination or face regular testing, mask mandates and travel restrictions.

In the private sector, a growing number of companies are also mandating COVID-19 vaccinations. United Airlines, meatpacker Tyson Foods Inc and Microsoft are requiring employees get vaccinated.

STURGIS CROWDS

The evolving pandemic and the rapid community spread spurred by the Delta variant have already prompted the cancellation of some large-scale events. Last week, organizers canceled the New York Auto Show that had been set for later this month.

The New Orleans Jazz Fest was canceled for the second straight year as Louisiana fights a severe outbreak.

But fears about the Delta variant seem to not have dampened the mood in Sturgis, a small town in South Dakota that welcomes hundreds of thousands of motorcycle enthusiasts for the annual Sturgis Motorcycle Rally.

This year's gathering, taking place Aug. 6-15, might already be attracting record crowds.

"It is one of the biggest crowds I have seen," Meade County Sheriff Ron Merwin said in an email. "I think there will definitely be some spread."

The city of Sturgis has partnered with health officials to provide COVID-19 self-test kits to rally-goes but the event does not require proof of vaccination or mask-wearing.

Last year, the rally became the super-spreader event that many feared it would become.

While cases and hospitalizations were relatively low in South Dakota when the event started on Aug. 7, 2020, three months later the state set a record for hospitalized COVID-19 patients and new infections.

In the month of November alone, the state lost 521 people to COVID-19, nearly three times the number of deaths reported in October, according to a Reuters tally.