Josh Lafair is guest blogging again. This time, he is comparing his home town of Austin, which shut down just days after its first case, to Nashville, which waited two weeks. Thanks Josh!
In my last post, I discussed the importance of reducing R0, the average number of new infections caused by each infected person, to below one in order to flatten the curve. This time, I want to explore how my home town, Austin, Texas, reacted to COVID-19 differently than Nashville, Tennessee, and use that information to predict each city’s respective outbreak. While Austin has almost twice the population, both cities are structured around a major college and are considered to be similar.
Travis County (which includes Austin), recorded its first case of Corona on March 13th, while Davidson County (which includes Nashville), recorded its first case of Corona on March 8th.
On March 17th, four days after Austin’s first recorded case, it had 6 total cases, and the Mayor ordered all bars and restaurants to be closed and limited social gatherings to less than 10 people.
On the other hand, Nashville waited a full two weeks after its first case to enact similar restrictions. On March 22nd, after it had already recorded 167 cases and 2 deaths, the Mayor of Nashville ordered all bars and restaurants to close and even issued a stay at home order. Two days later, the Mayor of Austin followed suit after recording a total of 79 cases and 0 deaths. Austin enacted closures after its first recorded cases. Nashville only closed after its first recorded deaths.
Where are these two cities now? As of April 6th, Travis County had 502 cases and 6 deaths while Davidson County had 1034 cases and 7 deaths (again, keep in mind that Travis County is twice the size). Below, is a graph that outlines the total number of infections for Travis County and Davidson County. In order to make a better comparison, I lined up the shutdown dates, and put a black vertical line at the date of shutdown.
While the lines appear parallel now, the later shutdown in Davidson appears to have allowed the case increase to continue on a steeper curve for longer (as always, the graph is on a log scale, so a straight line increase means exponential growth).
Let's again look at the timeline.
2020-03-08 Nashville Records First Case
2020-03-13 Austin Records First Case
2020-03-17 Austin Closes Bars and Restaurants 4 days after first case: 6 cases and 0 Deaths
2020-03-21 Nashville Records First Two Deaths
2020-03-22 Nashville Closes Bars and Restaurants and Orders Total shutdown 14 days after first case: 167 cases and 2 deaths
2020-03-24 Austin Orders Total Shutdown: 79 cases and 0 deaths
In terms of COVID-19, Nashville enacted its closures 10 days after Austin because it waited 14 days to issue government intervention after its first case. Austin only waited four. Austin closed down before it ever recorded its first death while Nashville closed a day after it recorded its first death. I think this contrast could be very telling for their futures.
Data from numerous sources suggest that it takes at least two weeks for someone with COVID-19to die. They also hypothesize that the death rate is around 1%. Using these numbers, it becomes clear that around 200 people were infected with COVID-19 in Nashville on March 7th, two weeks before there were any government closures.
Austin recorded its first death on March 27th. Therefore, there were around 100 people with COVID-19 on March 13th (this was also the day that Austin recorded its first case). Austin closed its bars and restaurants and limited social distancing four days after that.
So, what does this all mean? It’s hard to tell how bad each city's outbreak will be or already is because of the lack of testing kits. The numbers I’ve provided in terms of deaths are obviously rough. Evidently, at this point, all data associated with COVID-19 has been uncertain, and it almost always underestimates the situation a city is in. However, if city closures are as effective as everybody believes they are, Austin will probably peak earlier than Nashville, and Austin’s peak will be less severe, because the city began closing down earlier relative to its first recorded case.