A Tale of Two States

COVID-19 cases yesterday: Nebraska 309, Montana 2. Let's have a closer look at how the two states got there. Here is the graph of cases for Nebraska:

If we look at the blue curve that shows 7-day averages, it's a steady increase in cases. Nebraska was one of the last states to issue a "stay-at-home" order. Governor Ricketts announced the stay-at-home order on April 9. He used very short, simple sentences:

Note that the second rule states "use the six-foot rule as much as possible in the workplace".  The health department issued a somewhat more detailed description that included restaurant closings, but otherwise, businesses in Nebraska were allowed to remain open, even if social distancing was not possible.

Now let's look at Montana:

Montana had a rapidly increasing number until the end of March. Governor Bullock issued two executive orders on March 26 that include 10 pages of detailed restrictions. These included:

• An order to stay at home "to the greatest extend possible".
• Prohibition of "all public and private gatherings of any number of people", with very limited exceptions.
• Prohibition of all non-essential travel, and a restrictive definition of essential travel.
• Closures of non-essential businesses, with a detailed and restrictive description. For example, "Critical Trades" like Building and Construction were only allowed for "service providers who provide services that are necessary to maintaining the safety, sanitation, and essential operation of residences, Essential Activities, and Essential Businesses and Operations". 
• A paragraph that the restrictions were enforceable by the Attorney general, county attorneys, health departments, and other local authorities. 

Whereas the Governor of Nebraska was telling citizens that they were "doing a great job at complying with social distancing directives", the Governor of Montana outlined exactly what social distancing measures were expected from individuals and businesses.

At the beginning of April, the two states had a very similar number of COVID-19 cases. The governor of Montana issued strict restrictions and closed all non-essential businesses, which resulted in dramatic drop in new infections; for each of the last 6 days, Montana had between zero and two new COVID-19 cases. When Montana re-opens, its residents can feel reasonably safe.

In contrast, the governor of Nebraska took a "economy-friendly" approach that allowed most businesses to operate. Instead of outlining restrictions and expectations on how citizens should behave, he congratulated them on "doing a great job", and used sentence structures that are perhaps appropriate for toddlers. As a result, the number of new COVID-19 cases increased to  more than 300 per day, and appears to be still increasing rapidly.

Most other US states fall between these two examples. In general, there is a strong correlation between how quickly restrictions were issued, and how strict they were, and the growth or decline of new cases in a state.

Within the next months, it is highly likely that many states will see a dramatic increase in new COVID-19 infections as a result of the "re-opening" of the economy. Any governors that consider issuing new restrictions to reduce transmissions, rather than just "sacrificing the weak", would be well advised to look at the example of Nebraska and Montana. Of course, there are also many international examples of success in containing the COVID-19 epidemic, which include Taiwan, New Zealand, Australia, and Austria; some of these countries have been even more successful than Montana. But Montana is setting a good example for the US.
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The idea for this post is based on a article titled "Variation Among states in rate of coronavirus spread", which highlighted the discrepancies between Nebraska and Montana. The article uses a "slope" approach that is similar to what the "Data Trend Model" predictions use.