(CNN) - The United Kingdom has become the first country to approve an updated version of Moderna's Covid-19 vaccine booster that targets two coronavirus variants: the Omicron strain and the original virus from 2020.
"An updated version of the COVID-19 vaccine made by Moderna that targets two coronavirus variants (known as a "bivalent" vaccine) has today been approved for adult booster doses by the Medicines and Healthcare products Regulatory Agency (MHRA) after it was found to meet the UK regulator's standards of safety, quality and effectiveness," read an official government release Monday.
Half of the booster, called "Spikevax bivalent Original/Omicron," targets the original coronavirus strain while the other half targets Omicron, it said.
The UK government said that the decision to grant approval for the shot was endorsed by the MHRA, the government's independent expert scientific advisory body, after carefully reviewing the evidence.
It was approved following the results of a clinical trial, where Moderna reported that its booster targeting Omicron showed a stronger immune response against the variant.
The company said its updated booster also showed a "potent" response against the BA.4 and BA.5 subvariants.
The side effects were described by the MHRA as being the same as for the original Moderna booster dose and found to be "typically mild and self-resolving."
"No serious safety concerns were identified," the UK government release said.
As Covid-19 continues to mutate, MHRA Chief Executive Dr. June Raine said that the new Moderna booster will help keep communities protected.
"The first generation of COVID-19 vaccines being used in the UK continue to provide important protection against the disease and save lives. 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."
It is not yet clear who will be offered the booster or when.
The UK's Joint Committee on Vaccination and Immunisation (JCVI) will advise on the vaccine's rollout.
Stéphane Bancel, Chief Executive Officer of Moderna, said on Twitter he was "delighted" the vaccine had been approved.
"This represents the first authorization of an Omicron-containing bivalent vaccine, this bivalent vaccine has an important role to play in protecting people in the UK from Covid-19 as we enter the winter months," he said.
Moderna is not the only vaccine maker updating its Covid-19 vaccines.
In June, Pfizer and BioNTech tested two Covid-19 vaccine boosters to target the Omicron variant. The companies said that preliminary results show a substantially higher immune response than the current Covid-19 shots.