The UK will be the first country to begin clinical trials of a new coronavirus antibody treatment developed by drugs giant AstraZeneca aimed at people with a weakened immune system who cannot be vaccinated.

A participant in Wakefield, West Yorkshire, will be the first in the world to receive the pharmaceutical company’s new “antibody cocktail” as part of the trial to test whether it will prevent Covid-19 for up to year.

The clinical trial programme will recruit 5,000 participants, which includes 1,000 people from nine sites in the UK.

The aim of the trial is to evaluate the safety and effectiveness of a combination of two long-acting monoclonal antibodies – man-made proteins that act like natural human antibodies in the immune system.

Sir Mene Pangalos, executive vice president of biopharmaceuticals R&D at AstraZeneca, said the treatment, which can be injected or administered intravenously, is aimed at those who have a weakened immune system and cannot be vaccinated as well as those who are unlikely to respond to immunisation – which may include hundreds of thousands people in the UK.

We need people to sign up to this, particularly those vulnerable people over 60 who are immuno-suppressed, and may be at higher risk of developing severe disease

He said: “There is going to be a significant number of people – even in a world where vaccines are highly effective – who will not respond to vaccines, or in fact will not take vaccines.

“So having monoclonal antibodies as potential therapeutics is also important.”

The UK Government has an in-principle agreement to secure access to one million doses of the antibody combination, dubbed AZD7442, if it is successful in the phase three trials.

The trial aims to enrol adults who are at increased risk of Covid-19 infection or who are more likely to have an inadequate response to vaccination, and will include people from health care and care home settings.

Sir Mene said: “We need people to sign up to this [trial], particularly those vulnerable people over 60 who are immuno-suppressed, and may be at higher risk of developing severe disease.”

We are absolutely looking to protect those people who are immuno-suppressed or those people who need immediate protection

Initial results from the randomised control trial are expected to be published in the first half of 2021, although the trial is expected to last for 12 months.

Kate Bingham, chairwoman of the UK’s Vaccine Taskforce, said: “This is part of the portfolio to protect the whole UK.

“So, obviously, vaccines work in people who have a functional immune system.

“[But] if you are immuno-suppressed and you are going through bone marrow transplants, or indications or treatments that actually reduce your ability to mount an immune response, then this is basically the only current way of providing that short-term passive immunity.

“So we are absolutely looking to protect those people who are immuno-suppressed or those people who need immediate protection, because you will remember that vaccines typically take about six weeks to work.”

She said the NHS Vaccine Research Registry – a list of 340,000 volunteers willing to go into clinical trials – will provide some patients for the trial.

Sir Mene said the two antibodies have been engineered with a life-extension technology to make them effective for a longer period of time.

He said: “We think they will confer protection for between six, but more likely closer to 12 months, which makes them in effect, almost like a passive vaccination.”

Whilst it is unclear how much the antibody treatment will cost, Sir Mene said it will be “more expensive than vaccines”, but added “we hope to make it cost effective”.

Business Secretary Alok Sharma said: “I am very proud that the UK is the first country in the world to begin this invaluable study, and that a fifth of trial volunteers will be from Britain – a testament to our fantastic life sciences sector and the willingness of our people to come forward to help others.

“As we move closer to a Covid-19 vaccine, we must keep driving forward clinical trials for new and alternative treatments that protect our vulnerable, particularly those who cannot receive a vaccine.

“That is why we have procured one million doses of AstraZeneca’s long-acting antibody treatment if it meets robust safety and effectiveness standards.”