Why you should worry about Covid-19 (Mar 17)

I just made a spreadsheet with New York coronavirus data, to get an idea of how bad it is likely to get here, and when.

Looking at other countries, the most important factor is whether the hospital system is overwhelmed. If so (as in Wuhan, Iran and Italy)  the death rate is high, and it’s a national emergency. If not (as in Taiwan, Singapore, S Korea and most of China), then the pandemic is less of a disaster.

It takes 3 numbers to calculate the risk and timing:

1. 1. 1. Virus growth rate. World-wide outside China, cases are increasing by about 15% per day. NY cases are growing by 30% per day. Calculating from R₀ rate of spread (1.4 to 3.9 infections per case) and incubation period (5 days, range 2 to 14) gives numbers in about the same range.
      2. Hospital capacity. Different sources say 3,000 to 4,000 ICU beds in the state.
      3. Percent of confirmed cases that need intensive care. Most studies show it between 5% and 10%.

The most optimistic calculation says that NY will run out of ICU beds on April 15 (four weeks from today). The most pessimistic version says crisis hits March 31 (two weeks from today).

Different sources say the US has 45,000 to 95,000 ICU beds. Using the same logic, they all are filled sometime between April 3 and April 25.  Four weeks away, plus/minus 10 days. The math assumes that ICU beds are currently half full, but another 50% can be added on short notice.

Keep in mind that testing in the US has been woefully sparse. All confirmed counts are just a bare minimum. Actual infections could easily be 10x or 100x higher. However, that does not affect the timing by much. The numbers it changes just cancel out.

For local planning, many state health departments are now publishing case counts in each city or county. Wikipedia also is adding tracking pages for hard-hit states (search coronavirus + your state name).  Their basic pandemic page is at this link.  (update Mar 19: Politico has tracking of all Covid-19 test results for each state).

There’s a good visual of the NY growth curve on Wikipedia. Take your state’s current case count, and you can guess at what it will look like over the next week or two. All US states now have at least 1 reported case.

Also keep in mind that there’s a week or two lag between infection and testing/confirmation. It means that social distancing does not act quickly to reduce hospitalizations. You need to wait a week or two to see the benefits.

NY/NJ/CT closed all restaurants and bars yesterday. Everyone is panic-buying and preparing to hunker down. This is one situation where irrational fears are actually useful.

According to the math, we may just squeak by. To make it happen, social distancing has to reduce R₀ to 1 or below, and start really soon.

Dennis Kolva
Programming Director
TurtleSoft.com