Coronalinks 4/10: Second Derivative

https://slatestarcodex.com/2020/04/10/coronalinks-4-10-second-derivative/

The second derivative is the rate of growth of the rate of growth. Over the past few weeks, the second derivative of total coronavirus cases switched from positive (typical of exponential growth) to zero or negative (typical of linear or sublinear growth) in most European countries. Over the past few days, it switched from positive to zero/negative in the United States and the world as a whole. These are graphs of the rate of growth – notice how they go from shooting upward to being basically horizontal or downward-sloping (source).

This graph shows the numbers a little differently, (source), but you can see the same process going on in individual US cities

It would be premature to say we’re now winning the war on coronavirus. But we’ve stopped actively losing ground. If we were going to win, our first sign would be something like this. Current containment strategies are working.

As before, feel free to treat this as an open thread for all coronavirus-related issues. Everything here is speculative and not intended as medical advice.

The Bat Flu

SSC reader Trevor Klee has a great article on why humans keep getting diseases from bats (eg Ebola, SARS, Marburg virus, Nipah virus, coronavirus). He explains that because bats expend so much energy flying, they run higher body temperatures than other mammals, which degrades their DNA. Their DNA is such a mess that the usual immune system strategy of targeting suspicious DNA doesn’t work, so they accept constant low-grade infection with a bunch of viruses as a cost of doing business. Sometimes those viruses cross to humans, and then we get another bat-borne disease.