If Xi Jinping is to navigate an exit from the zero-Covid strategy of relentless lockdowns, mass testing and contact tracing, the Chinese president must overcome a steely bloc of resistance: tens of millions of elderly vaccine refuseniks.

Xi has been forced into a rare retreat after a drumbeat of youthful dissent against his draconian pandemic controls sparked unprecedented protests in more than 20 Chinese cities.

Standing in his way of an orderly exit are about 85mn people — one-third of the 267mn Chinese citizens in their 60s — who have not received a third vaccine dose needed for a high level of protection against the Omicron coronavirus variant. Among those aged 80 and over, the under-protected rate surges to about 60 per cent, or 21mn people.