Did the protests spread the coronavirus? Here are the Utah numbers and the national research.

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Let’s say you want to know how the recent social justice protests contributed to the spread of the coronavirus in Utah. How would you do it?

It’s a complicated question, because there are important reasons why you can expect infections to spread like wildfires in protests:

1. Large crowds of people not socially estranged. As we know, that is an important ingredient of an overcast event.

2. These protests often lasted for hours, long enough to spread the virus in previous superpreparation events.

3. Lots of chants and screams: an action that has been shown to spread the coronavirus. Just one minute out loud can emit 1,000 coronavirus-laden drops, which can then stay airborne for up to eight minutes, according to a US study published in May.

But there are also several mitigating factors:

1. The protests took place outdoors, allowing the drops containing the virus to disperse or evaporate. Even opening a window is a key step in preventing viral drops from persisting. An early study of 1,245 cases of coronavirus in China found that only one instance of transmission occurred outdoors: a close conversation where two men also shook hands.

2. Most of the protests also occurred on the day of June, which means that sunlight was at stake. When exposed to simulated sunlight in a laboratory, 90% of the virus was inactivated every 6.8 minutes.

4. Some people probably decided to stay home because of the protests instead of leaving. People certainly stayed home as a result of the curfew established in Salt Lake City.

So what set of factors won?

Probably the crudest possible way to find out is to look at the coronavirus case chart since May 29, the day of the first protest. And yes, the cases have increased significantly since that date.

But of course there are other reasonable explanations for the June jump. More businesses were opened, including some high-risk ones, like bars and cinemas. People took fewer precautions, spending more money on restaurants, for example. More Utahns went back to work. Some areas of the state turned green in the month, although those were rural counties far removed from the urban city of Salt Lake City.

Another way to investigate the issue is to compare the size of protests in each city and see if it correlates with the spread of the coronavirus in those areas. That’s what a document released this week by the National Bureau of Economic Research did: It took the 315 largest cities in the US, and compared the state of the coronavirus in the 10 days before George Floyd’s death and then 25 days. after. Places like Minneapolis see a huge growth in cases?

Typically, 25 days has been sufficient to detect past differences in case growth. Social distancing measures were shown to make a difference in cases only five to 10 days after their enactment, while another document showed growth in cases two weeks after local universities took spring break. If a difference in growth is detected, 25 days is enough to detect it.

Instead, the researchers found zero difference in case growth in cities with large protests compared to cities with small protests or without protests. In particular, their confidence intervals meant that they were at least 95% confident that any difference was less than 0.5 percentage points; Not only did they find a zero difference, but they were pretty sure of it.

They then looked to see if there was any difference in the coronavirus between cities where protests persisted for many days and where they did not. No difference. They looked to see if there was a difference between the violent protests. Still, there is no difference. Finally, they looked to see if there was a difference in the cities where the curfew was ordered. No difference.

Interestingly, the researchers also found that there was an increase in social distancing as a result of the protests, not by much, but by about 2%. People stayed home longer than they did in the week or two leading up to the protests. This could have been enough to mitigate any additional cases that might have been followed by major protests.

Of course, just because something is true about the aggregate at the national level it does not do so locally. The largest protests were in Salt Lake City proper, rather than the surrounding areas. If the protests caused the growth of the coronavirus, we would probably expect to see more proportional growth in Salt Lake City than the rest of the county. Thanks to the city-by-city coronavirus data from Salt Lake County, we can make that comparison.

I don’t see growth higher in Salt Lake City than the rest of Salt Lake County, proportionally. On the whole, growth looks pretty much the same, if anything it could be a bit higher in the non-SLC parts of the county.

If you’re a journalist, you can take an even more direct approach to find out if the coronavirus has spread significantly due to the protests in Salt Lake County – you can email the health department and ask.

After all, the health department tracks contacts extensively for each coronavirus case, calling and asking a series of questions to try to find out where each case was infected. We really are pretty good at tracing contacts in Utah – we’ve been able to find a specific source for over 70% of cases week after week.

Nicholas Rupp, communications manager for the Salt Lake County Health Department, told me that the department had found only five cases that “may be linked to attending a large community gathering as a protest.”

“These people became ill after attending such an event,” said Rupp, “and our epidemiologists have not identified any other likely sources of infection.”

Given that there have been 4,613 positive cases in Salt Lake County in June, according to the health department, and thousands of people who attended the protests over the course of several weeks, only five cases linked to the protests are an exceptionally low number. . To echo the authors of the document from the National Bureau of Economic Research, I would bet that those five cases were offset by the slight increase in people who stayed home due to the Salt Lake City curfews in the days after the biggest protests.

We can take some lessons for other activities here too. During the summer months, doing things outdoors with a mask on is low risk: the virus spreads and dies very quickly under those conditions. It’s even enough to significantly mitigate high-risk activities like crowding and yelling. Of course, I also recommend keeping physical distance when possible.

On the other hand, it shows how dangerous other forms of neglect can be: if our increase in cases is not due to protests, it is due to other factors. That means indoor transmission is to blame: in bars and restaurants, in all kinds of workplaces, and in our homes. We need to be vigilant in these places: closed spaces with poor ventilation are especially dangerous.

However, do you protest outdoors? I think we can safely conclude: they were not the source of our worrying growth of the coronavirus.