LONDON (AP) — The U.K. announced Sunday that it had reached its goal of giving at least one COVID-19 vaccine shot to the most vulnerable people in the country, increasing pressure on ministers to clarify when they will ease a lockdown imposed in early January.

More than 15 million people, or 22% of the U.K. population, have received their first shot. The figure includes most people in the government’s top four priority groups, including everyone over 75, frontline healthcare workers and nursing home staff and residents. Over 537,000 of them have also received their second dose.

“15,000,000! Amazing team,'' Nadhim Zahawi, the vaccines minister, said in a tweet that featured a red heart and three syringes. “We will not rest till we offer the vaccine to the whole of phase1 the 1-9 categories of the most vulnerable & all over 50s by end April and then all adults.''

British Prime Minister Boris Johnson plans to unveil his roadmap for easing restrictions on Feb. 22 amid signs that infection rates, hospitalizations and deaths have fallen sharply since England’s third national lockdown began on Jan. 4.

“This country has achieved an extraordinary feat — administering a total of 15 million jabs into the arms of some of the most vulnerable people in the country,'' Johnson said in a tweet.

Johnson said in England, everyone in the four top priority groups had been offered the vaccine. He plans to release further details on the vaccination effort on Monday.

Jockeying has already begun between those who want the measures lifted as soon as possible and those who fear moving too fast will lead to a resurgence of the virus.

Britain got a head start on its vaccination effort in December, when it became the first country to authorize widespread use of a COVID-19 shot. It ranks behind only Israel, 73%, the Seychelles, 53%, and the United Arab Emirates, 51% in the percentage of people who have received one dose, according to Oxford University. The U.S. is fifth at 15%.

At the same time, coronavirus lockdown rules that have closed schools, restaurants and nonessential shops in the U.K. are starting to pay off. The number of new infections, hospital admissions and deaths recorded over the past seven days have all dropped by more than 20% from the previous week.

When Johnson announced the lockdown, he said the government would review the measures in mid-February based on their success in controlling the pandemic and progress in the vaccination effort. Johnson’s first priority is to reopen schools, and he has promised to give schools two weeks notice to give teachers time to prepare.

Britain has reported over 117,000 virus-related deaths, the highest pandemic toll in Europe.

Mark Harper, a lawmaker from the ruling Conservative Party, has warned the government against “moving the goalposts” for deciding when to ease the lockdown.

Johnson should start by reopening schools, then gradually lift other restrictions as more people are vaccinated, said Harper, who leads a group of about 70 lawmakers who have lobbied the government to consider the negative economic and social impacts of the restrictions along with the health benefits.

“Once you have protected people from serious illness and from death, I don’t think these draconian restrictions of not being able to meet your family, not see your friends, not see your children, not see your parents, not visit people in care homes, I don’t think they are justifiable anymore,'' Harper told Times Radio.

After meeting the target for reaching the most vulnerable, U.K. authorities will progressively expand the vaccination drive to the next five priority groups until everyone over 50 and vulnerable younger people with health conditions that put them at higher risk from the virus have been offered the vaccine.

Public health officials say the top nine priority groups account for 99% of the deaths caused by COVID-19 so far.

While the vaccines currently authorized for use in the U.K. require two doses to ensure full protection against COVID-19, British authorities say one dose provides a significant level of protection.

Because of this, they have made it their priority to give the first dose to as many people as possible as quickly as possible. To do this, Britain is planning to give second doses after three months, instead of one month as recommended by the manufacturers.

Jeremy Farrar, director of the Wellcome Trust health think tank, said the number of COVID-19 infections in Britain is still too high to think about lifting the restrictions.

“We’ve made enormous progress … but the transmission is incredibly high still and we’ve got to get it lower,” he said.

There are other dangers on the horizon. U.K. government scientific advisers say the COVID-19 variant now predominant in the country may be up to 70% more deadly than previous variants, underscoring concerns about how mutations may change the characteristics of the disease.

The findings from the New and Emerging Respiratory Virus Threats Advisory Group, published Friday on the government’s website, builds on preliminary research released Jan. 21. The group, known as NERVTAG, includes experts from universities and public agencies across the U.K.

The new report is based on analysis of a dozen studies that found the so-called Kent variant, named after the county where it was first identified, is likely 30% to 70% more deadly than other variants. The studies compared hospitalization and death rates among people infected with the variant and those infected with other variants.

The results of the analysis are worrisome, said Dr. David Strain, a clinical senior lecturer at the University of Exeter Medical School and the clinical lead for COVID at the Royal Devon & Exeter Hospital.

“The higher transmissibility means that people who were previously at low risk of catching COVID (particularly younger fitter females) are now catching it and ending up in hospital,'' Strain said. “This is highlighted by the latest figures for hospitalization that now suggest almost 50:50 male to female ratio compared to this being predominantly in men during the first wave.''

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