SDSU Researchers Trace Surge In Coronavirus Cases To South Dakota Motorcycle Rally

Speaker 1: 00:00 Packing hundreds of thousands of masculine revelers into a small town line with bars amid a global pandemic seems like an ideal Petri dish in which to spread the virus. And that's exactly what happened a few weeks ago in Sturgis, South Dakota, an event that caused hundreds of thousands of new Corona virus cases in the U S that's, according to our report by San Diego state university's center for health economics and policy studies, Joseph Sabya director of the center and coauthor of that report joins me now welcome to midday edition. Thanks for having me. We'll start with the event itself. This is an annual festival attended by motorcycle riders from across the country, right? Speaker 2: 00:38 Yes, that's correct. This is in fact, the 80th Sturgis motorcycle rally. Speaker 1: 00:42 And what was the nature of this gathering? Why is it so ideal for this highly contagious Corona virus disruption? Speaker 2: 00:49 Sure. The centers for disease control and prevention has called large in-person gatherings of non-household members from outside of the local community, uh, that come together, uh, with minimal social distancing and mask wearing, uh, the highest risk for mass COVID-19 spread. And it seemed like the Sturgis motorcycle rally, uh, had all of these elements on steroids. In fact, uh, this was an event where nearly half a million individuals from all corners of the United States, uh, traveled to a town of about 7,000 residents, uh, and spent the better part of 10 days to two weeks was the, was the length of the event, lots of frequent interactions. Um, and then they went home to their home counties. So this, this kind of event is what the CDC has been warning about in terms of a, of a super spreader event. Speaker 1: 01:51 So it's an ideal event for you to study now, what were the findings of your study about the spread of the virus at the Sturgis festival? Speaker 2: 01:58 Sure. So my colleagues and I were interested in, in sort of two questions first, what was the impact of this rally on the locals spread of, of COVID-19? So we first look at need County, which houses, Sturgis, where most of these, uh, events happened. Uh, and we used anonymized cell phone beta, and we first documented that during this 10 day to two week period of the Sturgis rally, that there was a huge increase in the number of non-resident pings in Sturgis from all of those who had traveled there to attend the event. Then we were also able to measure foot traffic at the Sturgis event to see what they did once they got there. And we saw huge increases in foot traffic in restaurants, in bars, in non essential retail establishments in entertainment, venues in hotels, in camp grounds, and they need County. Uh, and in fact, in South Dakota in general, or there are very few mitigation policies, there are no worrying mandates. Speaker 2: 03:00 There are no capacity constraints in indoor dining and restaurants and bars. Also, we found about a 100 to 200% increase in COVID-19 cases in Meade County. We then extended that analysis to look at border counties of Meade County. And we also found evidence of COVID-19 spread in those border counties. And then we looked at the state of South Dakota and found evidence that this motorcycle rally led to about a 35% increase in COVID-19 cases in the state of South Dakota. So that was our analysis of local spread. But, but, but the issue with this, uh, Sturgis motorcycle rally is that over 90% of attendees do not reside in South Dakota, they're coming from all corners of the United States. So we looked outside of the state of South Dakota at those counties that contributed relatively high inflows into the Sturgis rally. And we looked at the trends in COVID-19 cases before and after this event. And we compared the trends in COVID-19 cases in high end flow counties to those counties that did not send any residents into the Sturgis motorcycle rally. And what we found is that in high inflow counties, COVID-19 case rates increased by about seven to 12% substantial increases in COVID-19 making this event a soup Speaker 1: 04:23 Right now. You also looked at Donald Trump's indoor rally and Tulsa and black lives matter protests and concluded. Those events did not contribute to a significant surge in COVID-19 cases. Why is that? What makes them different from the Sturgis event? Speaker 2: 04:38 A number of factors made the president's campaign rally in Tulsa, Oklahoma, and black lives matter protests that have been occurring across, uh, cities in the United States, different from, from the Sturgis rally. Uh, one is that, uh, the, the, uh, participants in the, uh, president's Tulsa rally and a black lives matter protests have largely been local residents, uh, as compared to individuals from, uh, who attended the Sturgis rally coming from all corners of the United States, uh, which is an additional risk factor for a super spreading event when you have lots of people coming from outside the local community. So that's one, the second is, uh, there were more mitigating, uh, activities taken by, uh, participants at those, uh, the Tulsa event and the black lives matter protests. Then at the Sturgis rally, uh, for example, many probe, many of the black lives matter protesters, uh, did wear masks participating in the protest. Speaker 2: 05:33 Uh, moreover many of the cities in which those protests took place had much stronger mitigation policies employees, uh, then did, uh, Sturgis or South Dakota as a whole, uh, at the president's Tulsa rally. Uh, but there was probably less mitigation that might've been going on, uh, at the individual participant level as compared to the black lives matter protest of the temperatures, every individual who went to the bank of Oklahoma arena for that event was taken up prior to entry. You don't see anything like that happen in Sturgis, but a third very important difference between these events is the way that local residents responded to the event in the cases of the president's rally and black lives matter protest. We found evidence that local residents responded to these events by increasing their stay at home behavior. In the case of Sturgis, we looked at what happened to stay at home behavior among local residents when that event took place. And in fact, we find evidence that that media and hours spent at home actually declined, uh, when that event took place, that is local residents were all in participating in the Sturgis event. So that's another reason why we saw more COVID-19 spread with the Sturgis event as compared to the other two events. Speaker 1: 06:52 And I should note your study has not been peer reviewed. There's been considerable pushback from officials in South Dakota and elsewhere over your findings. They say your report does not line up with what they know about the impact of the rally based on methods like contract tracing. And they also question the use of cell phone. Daddy, how do you, how do you respond to those critics Speaker 2: 07:12 In a world in which we had universal testing and contact tracing? Uh, we could rely entirely on, on numbers potentially that we, that we generated from such studies. Uh, but we don't. In fact, we get very small slices of the cases that we can attribute to particular events. Um, that's why we need other methods as well, to be able to document the full coven case effects of swoop, super spreader events like the Sturgis rally and anonymize cell phone data is a useful tool for us to be able to measure, uh, individuals movements and then be able to link a total COVID case growth from super spreader events to those events in a way that contract tracing, uh, cannot, uh, because it's not universal Speaker 1: 08:06 Speaking with Joseph Sabya director of San Diego state university center for health economics and policy studies. Thanks very much.