Pharmaceutical giant AstraZeneca has said the first volunteers have now been dosed in its clinical trial of a new drug to help prevent and treat Covid-19.

The group, which is also separately developing a Covid-19 vaccine together with scientists at Oxford University, said the drug – known as AZD7442 – is a combination of two monoclonal antibodies.

AstraZeneca said the trial, which will include up to 48 healthy volunteers in the UK aged 18 to 55, will look at the safety of the treatment, as well as the body’s reaction to the drug and how it processes it.

The Cambridge-headquartered group said the phase 1 clinical trial is an “important milestone” in the development of the drug, which has the potential to act as a preventative for people exposed to the virus, as well as to treat patients already infected with Covid-19.

A so-called monoclonal antibody combination works by mimicking the body’s natural antibodies.

The antibodies come from patients infected with coronavirus and were discovered by Vanderbilt University Medical Centre and then licensed to AstraZeneca in June.

Astra then boosts the combined antibodies so that they “afford at least six months of protection from Covid-19”.

Mene Pangalos, executive vice-president of biopharmaceuticals research and development at Astra, said: “This trial is an important milestone in the development of our monoclonal antibody combination to prevent or treat Covid-19.

“This combination of antibodies, coupled to our proprietary half-life extension technology, has the potential to improve both the effectiveness and durability of use, in addition to reducing the likelihood of viral resistance.”

If the trial is successful, Astra said it would look to move the treatment to late-stage phase 2 and phase 3 trials.

The trial is being funded by the US Defence Advanced Research Projects Agency and the Biomedical Advanced Research and Development Authority, which is part of the US Department of Health and Human Services.

It comes after Downing Street said on Monday the UK would be first in line for the coronavirus vaccine developed by Oxford University and Astra, once approved.

This followed reports that Donald Trump was considering granting emergency authorisation for it to be fast-tracked in the US.