What the new variants of covid-19 mean for human health

THE WINTER solstice may have passed, but in the land of covid-19 the nights are still growing longer. In recent weeks two variants of the coronavirus have spread with ferocious speed in Britain and South Africa. They have mutations that make them a lot more contagious. Although, so far, they do not seem to be any deadlier, for every ten people that older variants would infect in Britain the new one infects 15. Early data suggest that the South African variant burns just as fiercely.

Just now the world is rightly focused on approving, making and administering vaccines. Alas, it also needs to face up to the fact that before jabs come to the rescue, the new variants will spread, creating deep difficulties for policymakers.

Evolutionary biologists have shrugged at the appearance of the mutations: this is how viruses behave, for natural selection favours variants that are more transmissible and less deadly (see article). Some viruses that cause common colds may have started out as vicious as SARS-CoV-2 and moderated in their old age. Policymakers cannot afford to be so relaxed. A more transmissible covid-19 virus that is just as dangerous, as this variant is, means that hospitals may be overwhelmed. In England the majority of the population has been in...