A reader with a PhD in engineering and 35 years experience in advanced data analysis wrote to us regarding Sweden’s experience so far in dealing with the Wuhan coronavirus without locking down the country. He reports:
I did a quick look at the data coming out of Sweden with the data obtained from Worldometer, and have plotted the data on a per capita basis (positive cases vs 1M population) for Sweden and the US as well as an exponential fit to the data. The exponential fit was obtained by using β-µ=0.3 for both countries, where β and μ are the rates of infections and removals in the population, respectively. The quotient of β/μ is the contagion rate or R0 (R-naught) and the WHO is estimating R0 to be between 2.0 and 2.5 for this virus.
Two extremely interesting observations can be seen in the data. First, although Sweden had a higher initial case count on March 4 than the US, their positive cases are approximately 670 per 1M population on April 5th and now below the US per capita rate of 1020 per 1M population. Second, the early infection rate for both Sweden and the US are essentially identical. The dashed red lines in the plot, as noted above, are a fit to the data using an identical slope of 0.3. But then Sweden “breaks the curve” (i.e. changes the infection rate) without any extraordinary measures.
Something very interesting is going on with this virus. I’m sure some of the differences between Sweden and the US can be explained by overall population density, the number of large cities, number of people per household, etc. but the fact that Sweden has broken the curve without draconian measures should force a reexamination of our current models and lockdown strategy. Further, it is likely that Sweden will not experience a second wave of the virus since it appears that they can continue their current lifestyle without serious economic implications until a cure of vaccine is found, which is exactly what we need in the US.
I thank our reader for this contribution. As I said in my post about Sweden, the most probative comparison of data from Sweden is with Norway, which imposed a lockdown weeks ago. However, a comparison to the U.S. is also informative.
I should also note that, so far, the numbers from Norway don’t seem to show that it’s doing a better job than Sweden of preventing new Wuhan coronavirus infections.
For more on Sweden, see this article by John Fund and Joel Hay.