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People queue at London Bridge Vaccination Centre in London, England on Jan. 5, 2021.HENRY NICHOLLS/Reuters

The British government is banking on a dramatic increase in vaccinations and a controversial change in how the shots are administered to slow a surge of COVID-19 infections that health officials fear is out of control.

Britain is desperately ramping up its vaccination program to get ahead of a new variant of the virus that is sweeping across the country. The number of infections has jumped 70 per cent in the past two weeks, and the daily figure surpassed 60,000 for the first time Tuesday. Hospital admissions have also reached the highest level since the outbreak began, and officials from the National Health Service have said the system could be overwhelmed within three weeks.

The country has been put under a near-total lockdown while officials try to boost the number of vaccinations to about two million a week. That’s almost twice as many as the NHS administered in the past month.

“It’s a huge effort,” Prime Minister Boris Johnson said during a news conference Tuesday. “This is the biggest vaccination program in the history of this country.” He has pledged to vaccinate all long-term care home residents, hospital staff and everyone over the age of 70 by mid-February – more than 13 million people.

To reach that target, health officials have decided to delay administering second doses of the vaccines for up to three months and have encouraged doctors to squeeze an extra dose out of every vial. Each vial contains enough vaccine for five doses, but an extra dose can sometimes be extracted by using certain needles and syringes, health officials said.

The decision to alter the dosing schedule has been questioned by scientists who worry that the vaccines could lose their effectiveness if they are not administered as directed. Regulators in several countries, including the United States, have also raised concerns and have refused to follow Britain’s example. “Making such changes that are not supported by adequate scientific evidence may ultimately be counterproductive to public health,” the U.S. Food and Drug Administration said in a statement this week.

The three vaccines currently in use – by Pfizer-BioNTech, Moderna and Oxford-AstraZeneca – all require two doses, the second 21 days after the first or, in the case of the Moderna vaccine, 28 days. All of the vaccines were tested and approved by regulators on that basis.

However, last week Britain’s Joint Committee on Vaccination and Immunization, which advises the government, recommended delaying the second dose to 12 weeks in order to immediately vaccinate as many people as possible. The committee said its analysis of the testing data showed that all the vaccines were up to 90-per-cent effective after the first dose.

“Given the high level of protection afforded by the first dose, models suggest that initially vaccinating a greater number of people with a single dose will prevent more deaths and hospitalizations than vaccinating a smaller number of people with two doses,” the JCVI said.

Several scientists said there hasn’t been enough study to back up the committee’s conclusion. They added that it’s not clear how long the protection from the initial dose will last and that there are concerns the virus could mutate to get around partially vaccinated people. The Pfizer-BioNTech and Moderna vaccines are also based on genetic technology that has never been used before, which scientists argue makes altering the dosing regimen even more questionable.

“The recommendation of the JCVI to delay second vaccine doses across the board has caused controversy and confusion,” said Stephen Griffin, an associate professor in the school of medicine at the University of Leeds. “Given the tremendous effort and investment required to mount clinical trials on this scale, it feels unwise to alter the Pfizer protocol – put simply, if it ain’t broke, don’t fix it.”

So far Britain is the only country to adopt the 12-week dosing schedule, although Germany is considering a similar approach and Denmark has approved a six-week delay. In a joint statement this week, BioNTech and Pfizer cautioned against a delay beyond 21 days. “There is no data to demonstrate that protection after the first dose is sustained after 21 days,” the companies said.

British health officials have stood by their decision and argued that the country is facing an emergency. The British Society for Immunology, which represents clinicians and researchers who study the immune system, said it would have preferred to stick with the prescribed dosing schedule but added: “We recognize that a pragmatic approach in the short term is needed.”

Chris Whitty, the Chief Medical Officer for England, acknowledged Tuesday that there was a vigorous debate among scientists about the decision to delay the second dose, but he said the overall consensus was that the risk of diluting the effectiveness of the vaccines was small.

“The size of the increase in risk is sufficiently small that, measured against this ability to double the number of people who actually are vaccinated, the public-health arguments are really strongly for doing what we’ve decided to do,” Dr. Whitty said during a news conference Tuesday. “This is a sensible balance of risk.”

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