Covid cases are falling, herd immunity is approaching and even gloomy epidemiologists believe the worst of the crisis may soon be behind us.
But one niggling worry hangs over us like a cloud — the threat of another new coronavirus variant. Twice now, Britain’s war against the virus has been knocked off course by new mutations — first, just before Christmas when the Alpha variant spread like wildfire from Kent, and then in the spring when the Delta strain was imported from India.
Nowadays, every optimistic statement is tempered by an accompanying warning about variants. Boris Johnson promised that the road map out of lockdown was irreversible — but only as long as a “far more dangerous variant” does not emerge. Professor Chris Whitty, the
