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Scientist @fredhutch, studying viruses, evolution and immunity. Collection of #COVID19 threads here: https://bedford.io/misc/twitter/

Jun 8, 2020 12:11 AM
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I appreciate the feedback I’ve gotten on these estimates (and whether it’s even responsible to make them). A couple of things to emphasize here. 1/11

Trevor Bedford (@trvrb):
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
https://twitter.com/trvrb/status/1269395226541518849


  1. The numbers provided are really guesses at this point based on Fermi calculations (https://en.wikipedia.org/wiki/Fermi_problem). I could easily be off. Transmission in crowds outdoors with large mask compliance has not been measured. 2/11

My value of 1 transmission per day per infected individual attending a protest is a guess based on the Gangelt carnival study. We could easily have half this or less as well. 3/11


My estimates / guesses were born out of seeing others takes of massive spikes following protests and wanting to do my best to ground some estimates (even if speculative). If the epi modeling community leaves this as a vacuum it will be filled with takes from pundits. 4/11


My general guess / speculation is that the protests (and the police response) will increase the daily number of new infections by ~2-3%. This is not a massive spike in cases. But it’s still large in absolute numbers (just as the protests are large in absolute numbers). 5/11


Given feedback, I’d like to give an updated (highly speculative) range. At the lower end, I think possible to have 1500 new infections per day in protests with 600k participating. With R0 of 0.9 and IFR of 0.005%, we’d expect 15k downstream infections and 75 eventual deaths. 6/11


At the high end, I think perhaps possible to have 3000 new infections per day and with R0 of 0.95 and IFR of 0.01%, we’d expect 54k downstream infections and 540 eventual deaths. 7/11


I’d give a highly speculative “more than 50 and less 500” estimate for the number of eventual deaths for each day of protests. 8/11


  1. The protests and potential to transmit virus are on a background of general societal opening. It feels as though we’ve largely given up on controlling the epidemic and have resigned ourselves to living alongside it. 9/11 https://www.theatlantic.com/science/archive/2020/06/america-giving-up-on-pandemic/612796/

A small improvement in epidemic control (via #TestTraceIsolate or otherwise) will pay dividends in mitigating infections acquired at protests, but also in reducing overall mortality. We can try to fix the things that are broken rather than playing off a false dichotomy. 10/11


The harms of systemic racism are real and utterly pernicious. The hope is that the protests may lead to lasting reform. It is a cruel twist that the US’s inability to control the epidemic has made it dangerous to protest. 11/11 https://www.vox.com/science-and-health/2020/6/6/21279592/protest-pandemic-covid-19-risk-second-wave-systemic-racism