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A sign welcomes the public to the COVID-19 vaccination centre set up at Chester Racecourse, in Chester, northwest England, on Feb. 15, 2021.

OLI SCARFF/AFP/Getty Images

British Prime Minister Boris Johnson has hailed the early success of the country’s COVID-19 vaccination program and set a new target of inoculating everyone over the age of 50 by the end of April.

Britain has already vaccinated everyone over 70, as well as most front-line health care workers and all long-term care home residents. If the April target is met, more than half the adult population will have received at least one vaccine dose by May 1.

“This is an unprecedented national achievement, but it’s no moment to relax and in fact it’s the moment to accelerate,” Mr. Johnson said during a news conference Monday.

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The vaccination program has been seen as a lifeline for the United Kingdom, which has faced a brutal resurgence of the virus since December, when a new variant emerged in Kent, outside London. Studies have shown the variant is as much as 70 per cent more transmissible and 30 per cent deadlier than the original version of the virus.

The mutation has spread throughout Britain and to roughly 50 other countries, including Canada. “It’s going to sweep the world, in all probability,” said Sharon Peacock, who heads a network of institutions that track genetic changes in the virus. The COVID-19 Genomics UK Consortium has become a world leader in sequencing the virus, and Dr. Peacock told the BBC that she expected its work to continue for some time.

“Once we get on top of [the virus] or it mutates itself out of being virulent – causing disease – then we can stop worrying about it. But I think, looking into the future, we’re going to be doing [sequencing] for years. We’re still going to be doing this 10 years down the line, in my view.”

There have been some encouraging signs in the U.K. The number of new infections has fallen sharply in recent weeks and on Monday hit the lowest daily total since October. Deaths and hospital admissions have also been dropping. That’s owing largely to strict lockdown measures introduced on Boxing Day.

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The turnaround in cases and the success of the vaccination program have increased pressure on Mr. Johnson to ease the restrictions. He plans to announce a road map out of the lockdown next week and on Monday expressed optimism that some measures could be relaxed. “I’m very hopeful that we’ll be able to go ahead and open things up,” he said. “I think there’s been a big change, and the big change is that science is now unquestionably in the ascendancy over the disease.”

The vaccination program could begin to slow down in March when health officials begin offering booster shots to people who got their first dose in December.

There have also been concerns about vaccination rates among some ethnic communities. A study released Sunday by researchers at the University of Leicester showed that the vaccination rates among Black and South Asian hospital staff have been far lower than among white staff.

The researchers reviewed vaccination data for 19,000 workers at the University Hospitals of Leicester, one of the largest in Britain. The study found that 71 per cent of white staff had received the jab, whereas just 37 per cent of Black employees and 58.5 per cent of South Asians had been inoculated.

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The findings “give significant cause for concern,” wrote Kamlesh Khunti, a professor of medicine at the University of Leicester and a co-author of the study. “This adds significant weight to emerging data in the general population which also suggests reduced uptake in ethnic minority groups.”

On Monday Sir Simon Stevens, the chief executive of the National Health Service, said there was “real concern about the hesitancy on the part of some Black and South Asian communities” to be vaccinated. He added that health officials were working with religious and community leaders to address the issue. “Although the start [of vaccinations] was slower in terms of the uptake in some of those communities, we are now seeing meaningful progress,” he said during a news conference.

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