Bending the Coronavirus Curve

One of the main goals of the Coronavirus related stay at home orders is to reduce the number of deaths due to COVID19. I did some analysis of Johns Hopkins tracking data to see how much progress we are making in bending the curve.

I have seen some similar analysis on the number of cases over time by country, but that data is highly dependent on the testing regime used to identify COVID19 related cases. While it is more distressing to look at deaths, it seems to me to be a relatively more consistent measure across the countries.

This first chart shows the total number of deaths attributed to COVID19 in selected countries. I tried to match up the country death totals based on the day they reach approximately 20 total deaths. In other words, day 1 on this chart is the day that the country reported about 20 cumulative deaths from COVID19. The y-axis on the chart is logarithmic, which provides a visually more accurate portrayal of the growth rate over time. If the slope of the line is getting steeper then the growth rate is increasing. If the slope of the line is getting flatter then the growth rate is declining. We want to see the curve bending and becoming totally flat.

You can see a clear bend in the data from China, where the slope of the line started bending around day 11 or 12 after incurring 20 cumulative deaths from COVID19. The slope of the line for China continued to decline after that.

South Korea took very aggressive action early and started to bend its curve around day 4 or 5 after their first 20 deaths. This resulted in a very significant flattening of its curve.

Italy, Spain and the UK are showing some decrease in the rate of growth, but the curves have a long way to go before they flatten.

The data from Iran over the past week looks suspiciously close to the data from China. The Iranian data may be accurate, but the closeness of the numbers makes me wonder about whether it is accurate or not.

The US and France lines are still showing upward trends. However, you can see from the 3-day moving average chart below that they have made some progress in the last couple of days, however, the growth rate in the number of deaths is still very high.

The next few days will be very important to watch to see if the US and French trend lines continue or start to bend down.

The daily growth rate data is extremely noisy, so I decided to dampen it by looking at a 3-day moving average. The chart below looks at a 3-day moving average of the daily growth rate in the total number of deaths by country for the data in the chart above. The lines start on day 3 which gives you a reference point as the average growth rate three days after the country reached the 20 death point.

What we want to see in this chart is the lines decreasing overtime. Most of the trend lines are moving down as they move to the right. The French line seemed to be making progress, but then the growth rate spike up and then down again.

The US trendline is very concerning as it has been trending upwards. We need to see this line start to drop down or the US will experience a very significant increase in the number of deaths.

Please let me know you have any additional perspectives on these charts or other analyses which might shed light on whether we are bending the curve of this horrible virus.

#COVID19 #coronavirus