BARONESS Joan Bakewell is threatening the Government with legal action over delays to the second dose of the Pfizer/BioNTech vaccine.

The Labour peer said there were grounds to show the decision taken by ministers to delay the second dose by up to 12 weeks was unlawful.

Originally, those having the vaccine were told their doses would be given 21 days apart but the Government has now stretched the timeline for the second dose to between three and 12 weeks.

It did this following a recommendation from the Joint Committee on Vaccinations and Immunisation to give more people the first dose.

Baroness Bakewell has instructed the law firm Leigh Day to start proceedings in response to the new dosing policy, and names the respondent as Health Secretary Matt Hancock.

She said: ““Older people are in limbo: they need to know whether delaying the Pfizer vaccine is both safe and legal. The Government needs to make this clear.”

Pfizer recommends the second dose of its jab is given after 21 days, as set out in its clinical trials.

The company said “the safety and efficacy of the vaccine has not been evaluated on different dosing schedules…there is no data to demonstrate that protection after the first dose is sustained after 21 days.”

Meanwhile, the World Health Organisation (WHO) said “there is very little empiric data from the trials that underpin this type of recommendation”.

Other scientists, writing in the British Medical Journal (BMJ), said the new policy is “not based on data from the trial, but on an assumption of what would have happened if the second dose hadn’t been given at 21 days”.

However, other experts have defended the policy, saying it will save the most lives from Covid-19.

England’s deputy chief medical officer, Professor Jonathan Van-Tam, said the data showed that patients got “almost complete protection” from their first dose of the Pfizer vaccine and could wait for their second dose.

He said JCVI analysis showed the vaccine was 89% effective against Covid-19 in the period of 15 to 21 days after the first dose, and it was unlikely that such protection would decline severely in the 12 weeks after the jab.

“Simply put, every time we vaccinate someone a second time, we are not vaccinating someone else for the first time,” he wrote in the Mail on Sunday.

“It means we are missing an opportunity to greatly reduce the chances of the most vulnerable people getting severely ill from Covid-19.”

The second dose of the vaccine from Oxford University and AstraZeneca will also be administered up to 12 weeks later under the new policy.

Its clinical trial data showed that many of those given the jab had their second dose in varying timeframes.

Stephanie Hill, solicitor at Leigh Day, said: “We have sent a pre-action protocol letter to the Secretary of State for Health and Social Care following his decision to delay the second dose of the Pfizer Covid-19 vaccine.

“The Covid-19 pandemic has created exceptional challenges. Our client, like everybody, hopes that the vaccination programme will be rolled out as quickly as possible.

“It is crucial that any changes to the vaccination programme are made lawfully, in accordance with regulatory approval, and with the informed consent of patients.”

Baroness Bakewell is fundraising for the legal costs for the case.