Early tests showed the jab, developed by US biotechnology company Novavax, leads to high levels of virus-fighting antibodies being produced. The trial on 10,000 people will now see if the vaccine can prevent people getting ill.

The UK government has already ordered 60 million doses in case it proves successful.

The Novavax jab is only the second to enter large scale trials in the UK; the other has been developed by the University of Oxford.

Novavax are using traditional methods - proteins from the coronavirus that cannot replicate in the body and a chemical, called an adjuvant, to boost the immune response.

Ten thousand people will take part in the trial and at least a quarter of them will be over 65, the age-group most at risk of severe Covid-19.

Half will be given two doses of the vaccine, three weeks apart, and the rest will be given a dummy jab called a placebo.

However, it will take months - probably early 2021 - before we know if the vaccine is successful. — Agencies