UK and Russian scientists are teaming up to trial a combination of the Oxford-AstraZeneca and Sputnik V vaccines to see if protection against Covid-19 can be improved.

Mixing two similar vaccines could lead to a better immune response in people.

The trials, to be held in Russia, will involve over-18s, although it's not clear how many people will be involved.

Recently Oxford published resutls showing their jab was safe and effective in trials on people.

The researchers are still collecting data on the effectiveness of the vaccine in older age groups while waiting for approval from the UK regulator, the MHRA.

AstraZeneca said it was exploring combinations of different adenovirus vaccines to find out whether mixing them leads to a better immune response and, therefore, greater protection.

 The hope is combining different vaccines will give either stronger or longer-lasting immunity to the virus.

There are reasons to think this might be beneficial for the Oxford and the Sputnik V jabs.

 The British-made Oxford vaccine, developed in partnership with AstraZeneca, and the Russian Sputnik vaccine, developed by the Gamaleya Research Institute in Moscow, are similar because they both contain genetic material from the Sars-CoV-2 spike protein.