Hey, I'm Dan! I invest in early-stage startups at Madrona and write the DL, a weekly newsletter about tech in the PNW

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The three most important COVID-19 charts

I didn’t write about coronavirus last week because I thought everyone had done enough reading of their own, but it’s the only thing I read about now, so hard to avoid it for a second week! So here you are… the three most important charts for understanding the current state of coronavirus:


1. COVID-19 Cohort Chart by Country

Note: Y-axis here is logarithmic

Note: Y-axis here is logarithmic

One of the things we always look at in our investments is the performance of cohorts. Basically, set all of your customers to time = 0 and plot their performance over time to compare different segments and understand what’s working well and what isn’t working (here’s a great explainer).


Someone did a similar analysis (and here’s an interactive version) for COVID-19 cases by country, and it’s very illuminating. Here, you can see the oldest “cohorts” (South Korea, Italy, Iran) are roughly three weeks out from hitting 100 cases, and their case counts have exploded (Japan hasn’t done many tests).


Cohort charts are really helpful to predict what will happen in the future because you can compare historical data with current trends, and right now, most of the other countries that hit 100 cases two weeks ago look a lot like Italy, Iran, and South Korea.


With the data laid out like this, it’s clear there is no way we have a Hong Kong-like outcome in the US, but hopefully with more mitigation, our line will start to flatten out like South Korea and not follow Italy.


2. COVID-19 Death Rate vs. Seasonal Flu

This is an important chart because there is a still a lot of chatter about how hundreds of thousands of people die from the flu every year, and COVID-19 is not a big deal because there have only been a few dozen deaths in the US. Well here is a look at the death rate of the flu vs. COVID-19 for every age group: at every age, COVID is 10-20x deadlier.


Additionally, doctors and hospitals are seeing patients who are young, fit, and have no medical problems becoming critically ill, and Hong Kong has found that even after recovering from coronavirus, patients have seen long-term organ damage leading to 20-30% drops in lung function.


3. Cost of Waiting

Someone on Medium wrote a fantastic article on coronavirus with timelines, growth rates, fatality rates, data on testing, and projections. It’s definitely worth a read, but in case you don’t, this is the main takeaway.


Basically, this chart illustrates a model that loosely replicates the spread of COVID-19 in Hubei. He then modeled how much they could slow down the case growth by introducing social distancing to mitigate the spread of the disease. By implementing mitigation (i.e., social distancing) one day later, there would have been a 40% increase in the number of cases.


TL;DR: It’s going to get worse, it’s not even close to being a “bad flu,” stop hanging out with lots of people ASAP


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