COVID-19: Twin Peaks
When I wrote my last post on COVID-19 on June 12th there was a growing concern that a second wave was coming. The data was showing a rotation of new cases from the states that were affected early to states that had not suffered much in the early months of the outbreak. In the past 7 weeks the virus has not only exploded in those later-hit states but resurged in some of the early ones as well, particularly California.
At this point we can see a clear second peak forming in terms of new daily cases.
The second peak in daily deaths looks like it’s just now forming:
While the second peak in cases/day is actually much bigger than the first peak in April, we’re fortunate that the second peak in daily deaths looks like it’s going to be a bit smaller than the first. This is likely because of the large increase in the number of tests the US is running each day:
It seems odd however that the testing rate has also peaked. You’d think the US would want to keep testing rates high until the virus has more obviously been defeated. Unfortunately, US testing data is not great. Some states report combined antibody and infection tests while Texas, for example, is not including data from “rapid tests”.
While the positive test rate has been coming down, it is still higher than 5% and our low point in June.
Fortunately hospitalization data helps confirm the 2nd peak in cases.
The number of people hospitalized looks similar in the second peak (60,000) as it did in the first but the number of people on ventilators and in ICUs is a bit smaller. This lines up with the growing evidence that hospitals are getting better at treating those who are infected. In addition more younger people are getting infected now which is reducing mortality.
State-Level
At the state level we have about as many states where the number of cases are decreasing as those where the number of cases is increasing but the decreases are larger — particularly in the heavily hit states of Florida, Texas, California, and Arizona. Missouri, Illinois, and notably New Jersey are the states showing the top increases at the moment.
In terms of deaths, those cases which have shown the largest recent declines in cases have unfortunately experienced the largest increase in deaths over the past two weeks:
Let’s look more closely at the 3 states with the largest recent increases in fatalities:
While all three states show clear new peaks in cases, the number of fatalities is still climbing in all of them with perhaps a peak forming in Texas but fatality data there has been exceptionally noisy in the past two weeks.
Per Capita Analysis
The second wave and the current peak have hit different states than the first wave. Since the case fatality rate has been lower in the second wave, the states with the most total fatalities haven’t really changed. For example, while Florida is now one of the top 3 states in terms of total cases per capita, it is only 20th in terms of deaths per capita. New Jersey remains worst in per capita deaths while Louisiana is worst in per capita cases. Hawaii is at the opposite end of the spectrum by both measures which shows the advantage of being an island in terms of controlling viral spread.
The jupyter notebook for these analyses can be found on my GitHub.
