The appalling killing of George Floyd and video after video after video of police brutality cements the elemental *rightness* of the Black Lives Matter cause. 1/21
Since January, I've striven to provide as complete an accounting of the #COVID19 pandemic as I can. And so I feel it is my job as a scientist to provide my best estimate of the amount of viral transmission the protests are likely to cause. 2/21
There is no doubt that mass gatherings facilitate transmission. This study investigates seroprevalence in Gangelt, Germany, finding a 2.5X increase in rate of infection of those attending carnival celebrations (medrxiv.org/content/10.110…). 3/21 
As has been said, wearing masks and protesting outdoors has to help, but shouting, tear gas, pepper spray and closely packed jails will increase transmission potential. NYC alone has arrested over 2000 people in the past week (nytimes.com/2020/06/05/nyr…). 4/21
Here's my very rough guess at what's going on. Given the ~20k confirmed cases per day we have ~1.5M currently infected across the US (analysis from @youyanggu via covid19-projections.com). This implies a population prevalence of 0.5%. 5/21
I'm finding it difficult to get a source for the number of people attending protests across the US. Wikipedia tells me there are protests in over 400 cities. Houston was 60,000 on a single day (forbes.com/sites/christop…). DC may be over 100,000 today (nbcwashington.com/news/local/liv…). 6/21
This number is likely to be off, but I'll take 600k as number of daily protestors across the US. With a population prevalence of 0.5%, this would imply 3000 infected individuals attending protests daily. 7/21
Now, this is extremely difficult to estimate, but my rough guess would be that an infected individual would on average transmit to one further individual each day in the protest setting. 8/21
This is averaging over a great many instances where mask + social distancing keeps transmission from occurring and other instances where proximity / tear gas / arrest cause more substantial transmission. 9/21
Thus, we might expect ~3000 infections per day as a result of protests, occurring mostly within younger healthy individuals. The national Rt number is roughly 1, so we expect these ~3000 infections to then cause on average another ~3000 infections in the broader community. 10/21
Let's assume that the ~3000 infections in protestors will have few repercussions in terms of health, however, we should expect the ~3000 community infections to reflect the overall IFR of between 0.5% to 1% and so would result in 15-30 deaths. 11/21
I could be wrong about the 1 downstream infection. If it's, say 2, these numbers become ~6000 infections per day in protestors, ~ 6000 infections per day in the community and 30-60 deaths. 12/21
My take home here is that the additional infections driven by protests are likely currently small relative to the size of the US epidemic, about a 3% to 6% increase above the estimated ~100k daily infections in the US. 13/21
However, sustained protests by the same individuals risks amplification where prevalence among protestors increases beyond the background ~0.5%, which could cause these numbers to grow. 14/21
If the protests do drive transmission we should start to see confirmed cases tick up 6-8 days after protests began, so around ~June 7. It might be possible to measure this increase, but it will likely be difficult to pick out a protest-specific effect in total case counts. 15/21
Racism and state sponsored violence are critical public health issues. We should also acknowledge that the specific action of large-scale public protest at this moment during the COVID-19 pandemic may result in perhaps more than 10 but less than 100 deaths per day. 16/21
These deaths will likely be disproportionately among black individuals (covidtracking.com/race). 17/21
These immediate health impacts need to be weighed against the potential for long term reform. This piece outlines this dilemma. 18/21
Also to consider: things like casinos reopening have not engendered the hand-wringing that the protests have. Because of the pandemic, we're in a terrible situation where addressing systemic racism and bringing economy back online carry health risks. 19/21
Protestors can mitigate against transmission by following guidelines:
* quarantine if showing any symptoms
* wear a mask
* try to stay 6 apart
* use hand sanitizer
* avoid yelling / chanting and instead use drums or other noise makers
20/21
* quarantine if showing any symptoms
* wear a mask
* try to stay 6 apart
* use hand sanitizer
* avoid yelling / chanting and instead use drums or other noise makers
20/21
Police must seek responses that minimize transmission potential. Current responses of tear gas, pepper spray and jailing after curfew are actively exacerbating it. Deescalation is even more critical in light of COVID. 21/21
(Keep in mind that my numbers above represent a best guess in the absence of real data. They could be easily be off.)
