Coronavirus is evolving. Whether it gets deadlier or not may depend on us

It’s too early to interpret the data on Covid-19, in part because nobody knows how many people have been infected – and there are many other factors in the mix, such as the changing age profile of the patient population and improvements in care – but we may already be seeing viral evolution in tumbling death rates. As epidemiologist Andrew Noymer of the University of California, Irvine, has pointed out, this would happen anyway, in time. But here’s the thing: we can accelerate it, if we choose to. We probably already are, in some parts of the world.