Lack of certain antibodies would mean you don’t have an “immunity passport” and are therefore not allowed to venture out in public. Those who have them would be issued certificates to roam and restart economies — so the vulnerable can stay home.

The controversial prospect of extraditions from Hong Kong to mainland China has thrown fresh doubt on the city’s status as a global financial hub.

Health Secretary Matt Hancock said people who could prove their immunity to the coronavirus would be allowed to return to “normal life.”