How much should you worry about the “Indian variant”?

RANDOM ERRORS occur every time a virus copies itself, blips on the lettering of its genome, like those a child might make while copying a passage from a book. Most of the errors, known as mutations, make little difference to the virus’s impact on any people it infects. But some do. A variant of SARS-CoV-2 known as B.1.617 is widely suspected to have played a big part in the disastrous spread of covid-19 across India in recent months. Millions have caught it and other variants. Hundreds of thousands are dead. The “617” variant has now spread to 44 countries. To understand how worrying it is, it helps to look to Britain, whose viral-surveillance system is the best in the world, making it a useful observatory through which the rest of the world can understand the variant.

The COVID-19 Genomics UK Consortium first detected it in Britain in February, but cases stayed low for months. Now they are rising. Weekly infections of B.1.617.2, a further-mutated form, have more than doubled in the last seven days, from 520 to 1,313. On May 6th the government upgraded 617.2 to a “variant of concern”, the highest level of official alarm. On May 11th the World Health Organisation followed suit. How much should the world worry about the variant that has devastated India?