British researchers are to explore mixing doses of the Pfizer and AstraZeneca COVID-19 vaccines in a world first trial aimed at finding new ways to swiftly reduce coronavirus infections as new mutated variants emerge.

While thousands of individual changes have arisen as the virus mutates on replication and evolves into new variants, only a tiny minority are likely to be important or change the virus in an appreciable way, according to the British Medical Journal.

Among coronavirus variants currently most concerning for scientists and public health experts are the so-called British, South African and Brazilian variants, which appear to spread more swiftly than others.