But his senior colleague Michael Gove indicated the lockdown could last beyond the December 2 cut-off if it failed to bring infection rates down.

The leader of the main opposition Labour Party, Keir Starmer, also suggested it would be “madness” not to extend the measures if it had not been successful.

He argued for a shorter, “circuit-breaker” lockdown last month and accused Johnson of ignoring scientific advice to impose the measures sooner.

Boris Johnson announces new national lockdown for England

The prime minister sought to reassure business leaders concerned about the effect of the new round of closures on their bottom line.

“I want to thank you for the heroic efforts you’ve made,” he told the annual conference of the Confederation of British Industry. “Believe me we will end these autumn measures on December 2nd when they expire.”

The lockdown measures include a return to working from home where possible and the closure of all non-essential shops and services, including pubs, bars and restaurants.

Johnson, however, had been under pressure from some of his own Conservative MPs not to impose the new restrictions given the effect of the first lockdown on jobs and livelihoods.

Britain is among the hardest-hit countries in the world in the outbreak, with more than 47,000 deaths from just over 1 million positive cases.

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Coronavirus survives 28 days on glass and banknotes, says Australian study

Coronavirus survives 28 days on glass and banknotes, says Australian study

Meanwhile, doctors in England have been put on standby for the possible roll-out of a vaccine before Christmas, which would potentially turn the tide in the fight against the pandemic.

Simon Stevens, chief executive of the National Health Service in England, told the BBC on Wednesday that with more than 200 Covid-19 vaccines in development, one would “hopefully” be available in the first part of next year, but doctors would be “gearing up” in case it is ready sooner.

The UK’s drug regulator has started accelerated reviews of vaccines under development by Pfizer Inc and AstraZeneca Plc, as Britain gets ready to approve the first successful shot as quickly as possible.

Johnson’s government regards the emergence of a vaccine, as well as the development of treatments, as the best way to avoid future lockdowns and ease social-distancing rules.

Andrew Pollard, Chief Trial Investigator at the University of Oxford, said he’s optimistic results could come before the end of the year to show whether the experimental vaccine will work.

“We’re getting closer, but we’re not there yet,” he told a hearing of Parliament’s science committee on Wednesday. There’s a “small chance” a vaccine could begin to be distributed to people by Christmas, he said, adding that the time lines are not yet clear.

Coronavirus vaccine race: where are we and how far?

Ministers have said care home residents and workers will be first in line to receive a vaccine, followed by people aged 80 and over, followed by health care workers and then the wider population.

But Kate Bingham, chairwoman of the UK Vaccine Taskforce, warned last week the arrival of a vaccine may not bring an end to the pandemic.

“The first generation of vaccines is likely to be imperfect, and we should be prepared that they might not prevent infection but rather reduce symptoms, and, even then, might not work for everyone or for long,” she wrote in The Lancet medical journal.