Britain has become the first country to approve the mass rollout of a coronavirus vaccine that has passed large-scale clinical trials. This is a big moment. The pandemic is by no means over, but the launch of mass vaccinations marks the beginning of the end. The final lifting of restrictions placed on millions to halt the pandemic’s spread may now be in sight.

It also opens up the possibility of rapid economic growth. High savings rates and a return of economic confidence could combine with months of pent-up economic demand to lead to a new edition of the Roaring Twenties that followed the end of the first world war and the conquering of the Spanish flu. If coronavirus can be banished for good, millions may soon rush out to indulge themselves in all the ways in which they have recently been denied.

Such optimism could still turn out to be misplaced. Distribution of the vaccine, if it works, will not be smooth. Governments need to persuade millions of healthy, and often low-risk, people to accept a dose. The accelerated approval process means that its effects might not be fully understood; its efficacy, too, is uncertain. The Pfizer/BioNTech vaccine given emergency approval in the UK has not yet been approved by the US and the EU. A mass vaccination programme of this scale and speed has no precedent.