Britain has become the first country to approve a Covid-19 vaccine that targets both the original and Omicron variant of the virus.
The the UK medicines regulator (MHRA) approved the so-called bivalent vaccine made by US drug company Moderna as a booster for adults.
The agency's decision was based on clinical trial data that showed the booster triggered "a strong immune response" against both Omicron (BA.1) and the original 2020 virus, it said.
The MHRA also cited an exploratory analysis in which the shot was also found to generate a good immune response against the currently dominant Omicron offshoots BA.4 and BA.5.
"The first generation of Covid-19 vaccines being used in the UK continue to provide important protection against the disease and save lives," MHRA Chief Executive June Raine said in a statement.
"What this bivalent vaccine gives us is a sharpened tool in our armoury to help protect us against this disease as the virus continues to evolve."