I’d rather be writing about hurricanes (or the lack thereof), or the dust (some of which is now over the southeast), but … at the risk of annoying folks, I think it’s worth talking about Florida, testing, and why more testing isn’t the reason there are more positives (even though that’s “true”). But read on and there will be an embiggenable dust image and notes at the end.
There is a major misconception going around that the reason for the increase in the number of positives is that there is more testing. This is one of those things that is true, but misleading. So it’s worth a closer look, using Florida as an example because their numbers are now trending into “New York in April” territory if something doesn’t change. Two weeks ago (June 12th), Florida had tested 1,335,899 people. As of yesterday, they have tested 1,768,885 people – a 32 percent increase. But the number of positives increased from 70,971 to 122,960 – a 75% increase! Put another way, the positive test ratio (a key metric in epidemiology) consistently increased from 5.31% to 6.95%. In simple terms, the virus is still expanding faster than the testing.
Let’s contrast that with New York. Over the same two weeks, New York expanded testing by almost the same amount: 31 percent. But … the number of positives only increased by 2%, and the positive test ratio consistently dropped day by day from 13.63% to 10.63%. In other words, as New York tests more people, a fewer percentage of those people are testing positive. So the testing is “getting ahead” of the expansion of the virus.
What about Georgia? The positive test ratio was at 9.42% on June 12, had dropped to 9.18% on the 18th, but is now back up to 9.47%. Based on other data, that’s about what we expect, that 9 or 10% of the general population should be testing positive for this thing.
Some people are latching on to the fact that the hospitalization and fatality rates are dropping, and attributing that to the younger ages of people testing positive. The ratio of dead to positive does seem to have plummeted from 4.18% to 2.82% in Florida. But that may be misleading because of the 20 to 30 day lag between testing and mortality. if we use a 20 day lag, the number has been pretty constant over the last two weeks, dropping much more slowly from 5.92% to 5.52%. So let’s not get excited about that just yet …
OK, enough virus – let’s talk dust. While this is a larger than normal plume, it’s not terribly unusual. I think folks are more attuned to troubling signs and portents these days (you know it’s weird when people start calling grasshoppers locusts). While people with respiratory problems might have some problems (especially in the Caribbean, although in the SEUS as well but since you are wearing your mask 😛 …), it shouldn’t be much more than a light show for us at sunrise/sunset. Their are two reasons why this plume is more substantial than in most years. First, it has been a bit drier and windier at the surface in Africa, which picks up more dust. Second, the middle and upper level winds are more consistent, and stronger, blowing across the Atlantic.
Here’s the promised dust image as of 8:40am this morning … as always, you can click to make it larger (embiggen, for you scholarly types):