Measuring social distancing effects in reducing COVID-19 spread

Governor Jay Inslee said on 26 March 2020 that our state has shown a “modest improvement” in stemming the COVID-19 infection rate. [1] As a young engineer I learned: “You can’t manage what you can’t measure.”[2]

This graph is my attempt to measure the effectiveness of our current social distancing measures are using the daily count of COVID-19 cases in King and Snohomish county. I am comparing the actual cases (in yellow, labeled First Diff Actual) to an exponential model I used to project the spread of infection. [3] The solid blue, red and green lines are projected increases in daily new COVID-19 cases for three scenarios starting on 10 March: baseline (no social distancing- red line, 25% reduction due to social distancing – blue line , and 50% reduction due to social distancing – green line. Our modest improvement (the yellow data falling in between the read and blue lines) seems to track the effects of 25% reduction in COVID-19 spread due to social distancing. What does this mean for King and Snohomish county in the near future?

The figure below shows three possible scenarios. The red line projects about 10,000 COVID-19 cases on 7 April. This seems to be our current trajectory. This is a large improvement over the baseline blue line of 25,000 COVID-19 cases on 7 April if we had done nothing.

As a colleague pointed out to me, the cumulative data is easier to visualize using a logarithmic plot as follows:

Have we done enough? That’s a question each of us need to address. Our leaders, like Governor Inslee, have provided us the framework to follow, it’s up to us to follow as best we can. I will also suggest listening to an excellent TED talk from Bill Gates

I suggest listening to an excellent TED talk from Bill Gates on other ways to respond to our pandemic, he discusses isolation , testing and the future.

Notes and References

[1] Coronavirus daily news updates, March 27: What to know today about COVID-19 in the Seattle area, Washington state and the nation accessed 27 March 2020

[2] attributed to Peter Drucker, drilled into my from multiple bosses

[3] I derived my simple model as described in my post using results originally developed by a team from the Institute for Disease Modeling with some partners: Klein, D., Hagedorn, B., Cliff Kerr, H. H., Bedford, T., & Famulare, M. (2020). Working paper – model-based estimates of COVID19 burden in King and Snohomish counties through April 7, 2020Institute for Disease Modeling.

[4] Here’s a link to the underlying data and model I am using. Updated Covid19 Data SnoKing J Brew I will be updating this daily until 7 April 2020

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