A COVID-19 vaccine from Oxford University and AstraZeneca has been approved for use in the UK, paving the way for mass rollout.

The jab, which has been described as a “game changer”, was given the green light by the Medicines and Healthcare products Regulatory Agency (MHRA).

Health Secretary Matt Hancock said the approval is “fantastic news” and confirmed the rollout will begin on January 4.

“This is a moment to celebrate British innovation – not only are we responsible for discovering the first treatment to reduce mortality for Covid-19, this vaccine will be made available to some of the poorest regions of the world at a low cost, helping protect countless people from this awful disease,” he said.

“It is a tribute to the incredible UK scientists at Oxford University and AstraZeneca whose breakthrough will help to save lives around the world.”

It comes amid increasing strain on hospitals in England, where the number of Covid-19 patients is the highest it has been during the pandemic.

Mr Hancock is due to announce any changes to tier areas in a statement to the Commons on Wednesday.

With case rates rising in all regions of England, and record patient numbers, any changes are likely to involve areas moving up a tier rather than down.

The UK has ordered 100 million doses of the Oxford University vaccine – enough to vaccinate 50 million people.

A Department of Health and Social Care spokesman said: “The Government has today accepted the recommendation from the Medicines and Healthcare products Regulatory Agency (MHRA) to authorise Oxford University/AstraZeneca’s Covid-19 vaccine for use.

“This follows rigorous clinical trials and a thorough analysis of the data by experts at the MHRA, which has concluded that the vaccine has met its strict standards of safety, quality and effectiveness.”

The Joint Committee on Vaccination and Immunisation (JCVI), which advises ministers, will publish its latest guidance on who should receive the vaccine and in which order later.

Data published in The Lancet medical journal in early December showed the vaccine was 62% effective in preventing Covid-19 among a group of 4,440 people given two standard doses of the vaccine when compared with 4,455 people given a placebo drug.

Of 1,367 people given a half first dose of the vaccine followed by a full second dose, there was 90% protection against Covid-19 when compared with a control group of 1,374 people.

The overall Lancet data, which was peer-reviewed, set out full results from clinical trials of more than 20,000 people.

Among the people given the placebo drug, 10 were admitted to hospital with coronavirus, including two with severe Covid which resulted in one death.

But among those receiving the vaccine, there were no hospital admissions or severe cases.

People receiving the Oxford vaccine or the one from Pfizer/BioNTech, which is also being rolled out, will now receive their first dose of the vaccine followed by a second dose up to 12 weeks later.

The aim is to give as many people as possible a first dose of a Covid-19 vaccine.

The Department of Health spokesman said: “Having studied evidence on both the Pfizer/BioNTech and Oxford University/AstraZeneca vaccines, the JCVI has advised the priority should be to give as many people in at-risk groups their first dose, rather than providing the required two doses in as short a time as possible.

“Everyone will still receive their second dose and this will be within 12 weeks of their first. The second dose completes the course and is important for longer term protection.

“From today the NHS across the UK will prioritise giving the first dose of the vaccine to those in the most high-risk groups.

“With two vaccines now approved, we will be able to vaccinate a greater number of people who are at highest risk, protecting them from the disease and reducing mortality and hospitalisation.”

AstraZeneca chief executivde Pascal Soriot said: “Today is an important day for millions of people in the UK who will get access to this new vaccine.

“It has been shown to be effective, well-tolerated, simple to administer and is supplied by AstraZeneca at no profit.”

Professor Andrew Pollard, director of the Oxford Vaccine Group, who led the clinical trial, said: “The regulator’s assessment that this is a safe and effective vaccine is a landmark moment, and an endorsement of the huge effort from a devoted international team of researchers and our dedicated trial participants.

“Though this is just the beginning, we will start to get ahead of the pandemic, protect health and economies when the vulnerable are vaccinated everywhere, as many as possible as soon possible.”

During the Oxford vaccine trial, the half-dose followed by a full-dose regime came about as a result of an accident.

However, the MHRA was made aware of what happened and clinical trials for the vaccine were allowed to continue.

In an interview with the Sunday Times, Mr Soriot suggested that further data submitted to the regulator showed the vaccine could match the 95% efficacy achieved by the Pfizer/BioNTech and Moderna vaccines.

“We think we have figured out the winning formula and how to get efficacy that, after two doses, is up there with everybody else,” he said.