SD governor criticizes study suggesting Sturgis bike rally led to 260,000 COVID-19 cases
SIOUX FALLS, S.D. – A study by a California research group estimates that the Sturgis motorcycle rally in South Dakota led to more than 260,000 coronavirus cases in the month following the event.
Researchers from the Center for Health Economics and Policy Studies at San Diego State University published their findings Saturday in a 63-page report.
The estimate is dramatically more than the number of cases tied to the rally reported by both the South Dakota health department and the Associated Press.
South Dakota Gov. Kristi Noem on Tuesday said the study was "fiction," and she criticized journalists who reported on it.
The goal of the study was to estimate the impacts of a single "super-spreader" event on the spread of COVID-19. The same group has conducted similar studies on cases resulting from events like the nationwide Black Lives Matter rallies and the June political rally for President Donald Trump in Tulsa, Oklahoma.
Previously: First COVID-19 death linked to massive Sturgis biker rally; cases reported across the nation
Using cellphone data as part of their analysis, the researchers identified areas that saw lots of rallygoers and tracked cases before and after the event. Those findings, paired with a per-case cost estimate from another team of economists, conclude the rally may have generated a public health cost of about $12.2 billion.
"Even though the event benefited South Dakota economically, the majority of the health cost is being borne by the rest of the country," Andrew Friedson, one of four authors of the study, told the Sioux Falls Argus Leader, part of the USA TODAY Network, on Monday.
State epidemiologist: 'The results do not align with what we know'
Noem on Tuesday came to the defense of rally attendees while dealing harsh criticism to the study.
"Under the guise of academic research, this report is nothing short of an attack on those who exercised their personal freedom to attend Sturgis,” Noem said in the statement. "Predictably, some in the media breathlessly report on this non-peer reviewed model, built on incredibly faulty assumptions that do not reflect the actual facts and data here in South Dakota."
Noem's criticism comes hours after similar scrutiny from the state's top health officials.
The number of cases estimated in the study differs significantly from the number of cases tied to the rally reported by the South Dakota Department of Health. As of Tuesday, the state reported 124 cases among South Dakota residents who got sick after attending the rally.
The Associated Press as of last week identified 290 cases from 12 states tied to the rally.
"The results do not align with what we know for the impacts of the rally," state epidemiologist Josh Clayton said Tuesday.
That discrepancy is because the state is identifying specific cases through contact tracing. The study takes a different approach.
Instead of looking at contact tracing and trying to identify specific people who had the disease and passed it on to others, the San Diego researchers looked at the areas that sent the most people to the rally and how case trends changed after the event.
"We're never going to be able to contact trace every single person from Sturgis," Friedson said. "So if we want a good-faith estimate using, at the moment, the accepted statistical techniques ... this is the best number we're going to get in my opinion."
South Dakota Secretary of Health Kim Malsam-Rysdon disagreed with the methodology of the study Tuesday, questioning the link between cellphone data and cases. She and Clayton also noted that the research paper is not peer-reviewed at this point.
The public health cost estimate comes in large part from a separate study published last month by two economists. This study found nonfatal COVID-19 cases cost a weighted average of $46,000 per case. Using that number – and assuming all rally cases were nonfatal – the San Diego researchers estimated a public health cost of $12.2 billion.
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"This is enough to have paid each of the estimated 462,182 rally attendees $26,553.64 not to attend," the paper read.
Malsam-Rysdon said she hasn't seen the research behind that cost estimate, but she cautioned against taking it at face value.
"I would just caution you about putting too much stock into models ... that can't be verified by other factual numbers," Malsam-Rysdon said in reference to the study. "I think that is the case with that particular white paper."
Earlier studies on the Tulsa and Black Lives Matter rallies didn't find a subsequent uptick in cases, Friedson said, and that's largely because he and his co-authors found the new cases were offset by more people in those areas staying home during those events.
What's unique about Sturgis, though, is its small population. Even if everybody in town stayed home for the duration of the rally, it wouldn't be enough to offset the hundreds of thousands of attendees, Friedson said.
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This article originally appeared on Sioux Falls Argus Leader: Sturgis Rally: Study ties 260,000 COVID-19 cases to South Dakota event