How Bad Can the Coronavirus Get?

I recently watched a Youtube video on the exponential growth in the number of cases of the coronavirus outside of China. It mentioned a 15% increase each day. I decided to do my own analysis, and collected data from worldometers.info on coronavirus cases in five countries – France, Germany, Italy, Spain, and the U.S. All are experiencing exponential growth since March 1st.

The graph above shows the cumulative percent increase each day compared to the number of cases on March 1st. Italy has increased by a factor of 6 since the beginning of the month, while the number of cases in Spain is now 20 times greater than at the beginning of the month. France, Germany, and Spain are between these extremes, with a range between 12 and 14 times the number of cases at the beginning of the month.

Since the beginning of March, the number of cases in the U.S. has grown on average by 33.3% compared to the number of cases the day before. This kind of exponential growth could result in stunning increases over the next 30 days. If it is sustained, there will be over four million cases one month from now just in the U.S. The World Health Organization estimates the death rate from the coronavirus at 3.4%, With four million cases, there would be roughly 150,000 deaths from the coronavirus in the near future. I’ve heard multiple people say they do not believe that the coronavirus is as bad as the flu. The number of deaths estimated during the current flu season is estimated at 20,000, so it is possible that claim may not be true for long.

The spread of disease is a function of two factors – exposure and the likelihood of getting the disease once exposed to it. Reducing exposure by staying away from large crowds seems to be the most effective means to reduced the spread of the disease. Making changes now to limit exposure can make a big difference in the near future. Cutting the daily increase in the number of cases by 10 percentage points, to 23.3% per day, will result in a 90% decrease in the number of cases expected one month from now. Fortunately, action is being taken. Many universities are cutting out in-person classes for the foreseeable future. Companies are severely curtailing travel. Organizations are cancelling or postponing workshops and conferences. Some people are calling it hysteria, but this is the right action to take given the risk we face.