The Pfizer/BioNTech vaccine is an updated booster and the second bivalent to receive approval from the medicines watchdog.
The MHRA has found the booster meets the UK safety, quality and effectiveness standards.
The booster has also been approved by the Commission on Human Medicines, which advises ministers on the safety of products.
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The vaccine is approved for those aged 12 and over as a booster dose. Half the vaccine (15 micrograms) targets the original strain and the other half (15 micrograms) targets Omicron variants.
Common side-effects with the new bivalent vaccine were typically the same as those seen for other versions and were usually mild.
No new safety concerns were found, the MHRA said.
The new Pfizer/BioNTech bivalent vaccine had already been approved last month by the EU, United States and Canada.
A bivalent vaccine includes a component of the original virus strain and a component of omicron to provide better, longer-lasting protection.
