Britain on Monday became the first country to approve an updated COVID-19 vaccine by Moderna that protects users against the original coronavirus strain and the more contagious Omicron variant.

The country's Medicines and Healthcare products Regulatory Agency announced it signed off on its use as an adult booster dose, saying it met British standards of safety, quality and effectiveness.

The agency said it based its decision on trials that showed the Moderna vaccine triggers a strong immune response against Omicron, as well as having a "good immune response" against its new sub-variants BA.4 and BA.5.

"The virus ... is continually evolving in order to evade the immunity provided by vaccines," said Munir Pirmohamed, chair of the Commission on Human Medicines in a statement.

"This novel bivalent vaccine represents the next step in the development of vaccines to combat the virus, with its ability to lead to a broader immune response than the original vaccine."

The agency said the Joint Committee on Vaccination and Immunization will now advise on how this vaccine should be offered as part of the deployment program.

According to the Centers for Disease Control and Prevention, the BA.5 and BA.5 sub-variants of the coronavirus make up about 94% of all new cases in the United States, with BA.5 blamed for more than 88% of those cases.

President Joe Biden was diagnosed with then BA.5 subvariant on July 21 and shortly after overcoming it was hit with a rebound infection. He was cleared to resume his normal presidential duties on Aug. 7.

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