By: Eric Gundersen
NextStrain is tracking the spread of SARS-CoV-2 by sampling 3,170 genomes between December 2019 and April 2020 and open-sourcing the data to increase epidemiological understanding and improve public health responses. Historically, this platform has been used by the World Health Organization’s Global Influenza Surveillance and Response System (GISRS) to aid in vaccine strain selection for seasonal influenza viruses.
The tool helps us understand today’s discovery that the first coronavirus death in the United States occurred in California in early February, signaling the virus may have been spreading — and claiming its first victims— in the United States weeks earlier than previously thought.
“The fact that there were deaths related to COVID back in early February is very significant, because it means the virus was around for a lot longer than was initially realized. It’s been around for a while, and it’s probably been spreading in the community for quite some time.”
— Jeff Smith, physician and county executive in Santa Clara, CA, as quoted in The Washington Post
Trevor Bedford, a scientist at the Fred Hutchinson Cancer Research Institute who studies the spread and evolution of viruses, co-developed NextStrain. Here’s his analysis of today’s news (read the full thread here):
I wanted to respond to news of #COVID19 death in Santa Clara County on Feb 6. This is an interesting, if slightly puzzling, data point. 1/9
— @trvrb
We know that there is very little genetic diversity in global samples of SARS-CoV-2, which points to emergence in ~Nov 2019 in Wuhan, China. We know that once community spread is established it ramps quickly in the absence of social distancing. 2/9
— @trvrb
With a 3-day doubling, we can go from a single infection at day 0 to ~1000 infections at day 30. This rapidity of epidemic spread is visible repeatedly across epidemics including New York, Italy and France. Figure from @hsalje et al. (https://t.co/RbCx697sMs). 4/9
— @trvrb
Additionally, if we look at a transmission chain in the US, we see that it rapidly bounces between states owing to the level of within-US travel. 5/9 https://t.co/MlgjZwtfG9
— @trvrb
The report of a death in Santa Clara on Feb 6 does not effect my overall timeline of first introductions occurring in the US in Jan 2020 into locations with strong travel connections to China. This death is likely part of one of these early transmission chains. 6/9
— @trvrb
Maps are helping the global research community tell the stories behind their charts and graphs. This more detailed understanding of COVID’s spread — and how we can stop it — allows policymakers to target their restrictions on day-to-day activities more narrowly, minimizing the economic and psychological toll of social distancing.
Are you building with NextStrain’s open-source data? Share what you build with us using #BuiltWithMapbox. We’re proud to support builders of COVID-19 apps.
eric gundersen (@ericg) | Twitter
Maps feature data from Mapbox and OpenStreetMap and their data partners.
NextStrain: Tracking the spread of COVID-19 before social distancing was originally published in maps for developers on Medium, where people are continuing the conversation by highlighting and responding to this story.