Sturgis motorcycle event produced 600 percent surge in COVID-19 cases — and revealed the power of the delta variant

Dr. Ashish K. Jha, dean of the Brown School of Public Heath, penned a column in the Washington Post explaining how important the annual Sturgis motorcycle rally in South Dakota was in understanding the power of the delta variant.

Thus far, the infection numbers have increased more than 600 percent in South Dakota since the Sturgis rally. The pandemic has been raging for over a year, and South Dakota was ground-zero for the midwestern outbreaks. It was so bad in the state that about half of South Dakotans have immunity because they've been infected by COVID-19. After the vaccine became available, about half of the state has gotten the shot.

Dr. Jha explained that you can reasonably assume that there is some overlap between those two groups. So a solid part of the population should have immunity from the virus or be covered by the vaccine, yet they've still seen a significant increase in cases. He noted this is the inadvertent experiment that reveals the strength and power of the delta variant.

In Massachusetts, the July 4 weekend led to spikes in cases, but in that case, "numbers peaked quickly, dwindled and were gone three weeks later. There were very few hospitalizations and no deaths. Why? Because most of the people in Provincetown were vaccinated, wrote Dr. Jha. "That may be an indicator that population immunity from vaccinations is better and more protective than immunity from infections."

"We can expect to see big increases in other states, too, since bikers returned home from the event. Last year, after Sturgis, we saw massive outbreaks across the Dakotas, Wyoming, Indiana, even Nevada. Much of the region was aflame because of Sturgis, probably causing thousands of deaths," he estimated.

Chicago's Lollapalooza happened about a month ago, and at least one doctor said that there hadn't been evidence that it was a super-spreader event. It was among the country's first large outdoor festivals, and it required proof of vaccination or a negative test within 72 hours before. However, there were some reports that those working the entry points weren't checking the cards all that closely.

Still, thus far, only 203 attendees have tested positive for COVID-19 since Lollapalooza. That's about 0.05 percent of people who attended.

It gives important data about unmasked outdoor events at a time some states are allowing them. Concert giant Live Nation will require vaccination or negative tests moving forward. The Eagles concert at Madison Square Garden required proof of vaccination, as will the upcoming "We Love NYC Homecoming Concert." This could set the standard for returning to normal as more data comes in from the events.

That can give indications of the power of the delta variant at outdoor events vs. indoor ones.

"At Sturgis, it is unlikely that the outdoor bike rallies were a problem," he said. "Most of the spread likely happened in the evenings, when people crowded into bars and restaurants, most unvaccinated, all unmasked. Large gatherings that work on keeping indoor spaces safe through vaccinations, masking, ventilation, and other techniques can keep the entire gathering safer."

On the heels of the Labor Day weekend, another chunk of data will reveal the impact of the vaccines, and the assumption is that with vaccines, ventilation, masks and care, things can safely return to normal.