New cases of Covid-19 declining in AZ and FL

There was a lot of press given to the rapid increase in cases of Covid-19 in Southern and Western states in July, but less well reported has been the dramatic decline that has occurred since then in some of those states like Arizona and Florida.  In the week from June 29th to July 5th, the seven day average of new cases was around 3900 and in the week from August 15th to August 21st this average declined to around 430, a drop of almost 90% in just around 7-8 weeks.  In addition, Florida saw their number of new Covid-19 cases drop from 12,000 a day in mid-July (using the 7 day moving average) all the way down to around 4,000 in the latest week, a drop of almost 70% in just 5 to 6 weeks.  

One important thing to note is that in late March states across the US took dramatic steps to reduce the transmission rate to below one new case for every current case (down from perhaps 3 from before the restrictions), but then this transmission rate rose above 1 again once restrictions were loosened.  It didn't turn out to be that difficult for policymakers to lower the transmission rate below 1 again in a lot of states, and the nature of this particular virus is that the number of new cases go down a lot quite quickly once you get the transmission rate below 1.  My rule of thumb in China was that once they implemented their full set of restrictions, the number of new cases there went down by 90% every two weeks, but Arizona has shown us that even more moderate restrictions can reduce the number of new cases by 90% in just 7 to 8 weeks.  If Arizona could keep up their current level of restrictions for another two months the number of new cases could drop below 40 per day, which is enough to deal with through rapid testing and thorough contact tracing by itself.  

That's why I think it's especially important to follow the recommendations of infectious disease expert Michael Osterholm and Minneapolis Federal Reserve President Neel Kashkari and go through a strict 6 week lockdown so we can get the virus under control.  If the restrictions were as strict as China, a 6 week lockdown could reduce the number of new cases by 99.9%, but even more modest restrictions somewhere in between China's efforts and Arizona's efforts could reduce the number of new cases per day by over 95%.  Then it might be possible to have in class learning for our students and resumption of more economic activity, and a 6 week sacrifice would not be asking too much. Clearly this is better than our current approach, which is simply to muddle through until a vaccine arrives, and really does merit serious consideration.