The UK government has signed a fourth coronavirus vaccine deal, securing up to 60 million doses of an experimental treatment being developed by drug giants GSK and Sanofi.

Regulatory approval could be achieved by the first half of 2021 if trials are successful, according to Sanofi, which is leading the vaccine's clinical development.

The government has already signed up for 100 million doses of the Oxford University vaccine being developed by AstraZeneca.
It has also secured another 90 million doses of two other promising vaccines.

However, it is still uncertain which - if any - of the vaccines will work.