In response to yesterday’s post, I received a few comments concerned that the drop in new coronavirus cases in Arizona was due to decreased numbers of COVID-19 tests being performed. State test reporting has been a problem, with many states having been inconsistent in how they are reporting their numbers. I have written before that a few states, including Virginia, were adding antibody test positives to their test numbers of new COVID-19 cases. Since antibody tests do not identify new cases of COVID-19, rather simply show who had been infected, this was inflating both the number of tests and the number of “new cases.”
In addition, some had suggested that the entire recent increase in COVID-19 infections in several states was due to increased testing. This also was incorrect as the rate of positive tests went up, not simply the numbers. To make sure that the decrease in COVID-19 infections we are now seeing is not simply the result of decreased testing, I looked at several different measures of disease activity in these states.
Again, the Rt numbers for COVID-19 in several of these states are decreasing, with Texas, Florida, and Arizona just below 1.0. This clearly suggests the infection is contracting. I also examined testing numbers, rates of positive tests, and average rates of positive tests in these three states from the Johns Hopkins database.
I also looked at hospitalizations due to COVID on the ARIZONA DEPARTMENT OF HEALTH SERVICES website. This provided the clear data about the trend in COVID-19, and clearly shows a decrease.
This website also shows a more dramatic decrease in confirmed infections than the Hopkins data.
For a contrast, the Hopkins data shows a different story in Kentucky, where testing data is poor but appears to show an increase in the rate of positive tests, and Michigan where the disease remains suppressed.
This week I have obviously spent quite a bit of time on the infection rates in these state. I think it was important to make sure the decrease that is being seen is real. Since the media is ignoring this, I also wanted to make the point that these outbreaks do not continue forever and may be self limited in ways we don’t yet understand. I will continue to monitor this and address it again in the future.