Some doctors in Britain plan to challenge the instructions to delay shots for vaccine increases.

Some family doctors in Britain said on Thursday that they would challenge the government’s order to postpone patients’ appointments for a second dose of coronavirus vaccine, a sign of discomfort in the medical community over Britain’s new plan to shots delay as a way to get more people the partial protection of a single dose.

British doctors, who have been instructed to start rescheduling the second dose of appointments for next week, said they were reluctant to ask older, vulnerable patients to wait an extra two months for their Pfizer-BioNTech vaccine admissions. They said the patients relied on having full protection of two doses, that they had arranged caregivers to come to their doctors’ offices, and that it would be impossible for them to rely on a new and untested vaccination strategy.

In addition, it is logistically impossible to contact thousands of elderly patients within a few days and then fill it with first recipients.

The British Medical Association, a trade union for doctors, said on Thursday it would support doctors who decided to hold the second dose of appointments booked for January.

“It is tremendous and openly unfair for tens of thousands of our most dangerous patients to try to reschedule their appointments now,” said Dr. Richard Vautrey, chairman of the union’s GP committee, said in a statement. “The government needs to see that it is only right that existing discussions be honored for the oldest and most vulnerable members of our society, and it should also publish a scientifically validated justification for its new approach as soon as possible.”

A spokesman for the UK National Health Service said in a statement that the service provided GPs with ‘extra financial and logistical support’ to help ensure thousands received the vaccine more quickly. ‘

“The NHS must follow the new guidelines,” the statement said, “to increase the number of vulnerable people protected from Covid over the next three months, which could save thousands of lives.”

The postponement of the second vaccine dose could double the number of people who will soon get a shot and eventually ease the toll of the virus in Britain, where hospitals face a deluge of cases of a new and more contagious coronavirus variant come. While one might be better off getting the second dose right away, some scientists have said that society as a whole will benefit if more people get the partial protection of a single dose for the time being.

However, other scientists believe that Britain has exceeded the available evidence, and that older people and health workers could possibly leave the full protection of two vaccine doses amid the terrible winter push. Britain made the decision without the public meetings or extensive briefings that preceded U.S. regulatory decisions. No trials have explicitly tested the effectiveness of a single shot.

And what limited evidence exists about the protection offered by a single dose has clashed with scientists’ fears that antibody responses would diminish over time and possibly fall below a protective threshold.

Some GPs in Britain have said they are uncomfortable with a lack of evidence showing that patients will be protected against Covid-19 for weeks after a single ingestion of the Pfizer-BioNTech vaccine.

“I have been instructed to break my promise to my elderly patients,” said Dr. Helen Salisbury, a family doctor in Oxford, Said on Twitter on Thursday morning, “And use a vaccine outside the evidence and approved schedule, which is likely to jeopardize it.”