SARS-CoV-2 is following the evolutionary rule book

NATURAL SELECTION is a powerful force. In circumstances that are still disputed, it took a bat coronavirus and adapted it to people instead. The result has spread around the globe. Now, in two independent but coincidental events, it has modified that virus still further, creating new variants which are displacing the original versions. It looks possible that one or other of these novel viruses will itself soon become a dominant form of SARS-CoV-2.

Knowledge of both became widespread in mid-December. In Britain, a set of researchers called the Covid-19 Genomics uK Consortium (COG-UK) published the genetic sequence of variant B.1.1.7, and NERVTAG, a group that studies emerging viral threats, advised the government that this version of the virus was 67-75% more transmissible than those already circulating in the country. In South Africa, meanwhile, Salim Abdool Kalim, a leading epidemiologist, briefed the country on all three television channels about a variant called 501.v2 which, by then, was accounting for almost 90% of new covid-19 infections in the province of Western Cape.

Britain responded on December 19th, by tightening restrictions already in place. South Africa’s response came on December 28th, in the wake of its millionth recorded case of the illness, with measures that extended a night-time curfew by two hours...