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. Oxford recently published results 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