• Another excellent Morning item from David Leonhardt in the NYT. He discusses virulence (severity) and contagiousness of the delta variant and does a very good job of it. The quick summary: it’s a lot more contagious, but probably not much (or any) more virulent. This comports with the usual evolutionary selection pressures operant in a massive pandemic – the mutant virus that spreads more easily (is more contagious) can reproduce more efficiently by infecting many more hosts. But if it kills too many hosts too quickly (more virulent) it won’t be able to reproduce and spread as efficiently. The biggest issue for delta is that it is so contagious it will likely keep a huge portion of the world’s unvaccinated population infected for many months, and even if not more virulent, big numbers of infection mean more severely ill folks and deaths. And of course a large pool of infected individuals provides ample opportunity for more mutations to arise that might be more contagious still, more virulent, or escape vaccine induced immunity.