The MHRA’s decision was based on clinical trial data that showed the booster triggered “a strong immune response” against Omicron (BA.1) and the original 2020 virus, it said.

Britain, the first country to approve a coronavirus vaccine in late 2020, has now also given the green light for the first time to a variant-adapted vaccine that targets both the original and Omicron version of the virus.

The UK medicines regulator (MHRA) granted the so-called bivalent vaccine made by US pharmaceutical company Moderna conditional approval as an adult booster on Monday. Britain’s Joint Committee for Vaccination and Immunization (JCVI) is now expected to issue a recommendation soon on how the vaccine should be rolled out in the country.

The MHRA’s decision was based on clinical trial data that showed the booster triggered “a strong immune response” against Omicron (BA.1) and the original 2020 virus, it said. Moderna said in June that trial data showed that when given as a fourth dose, the variant-adapted vaccine increased virus-neutralizing antibodies against Omicron eight-fold.

The MHRA also cited an exploratory analysis in which the injection was found to elicit a “good immune response” against the currently dominant branches of Omicron BA.4 and BA.5. According to Moderna, the trial data showed that the levels of antibodies generated by the variant-adapted boost against the subvariants were 1.69 times higher than those given the original boost.

No serious safety issues were identified with Moderna’s new formulation, the MHRA added on Monday.

The UK government said last month that a vaccine booster program would start in “early autumn” and that shots would be offered to people over 50, people in clinical risk groups, frontline workers and nursing home staff seniors. While existing COVID-19 vaccines continue to provide good protection against hospitalization and death, vaccine effectiveness has been affected as the virus has evolved.

“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 sharp tool in our arsenal to help protect us against this disease as the virus continues to evolve.”

The UK Health and Safety Agency (UKHSA), which oversees vaccine procurement among other responsibilities, did not immediately respond to a request for comment.

Other approvals

Officials at the European Medicines Agency (EMA) expect vaccines tailored to the COVID variant to be approved in the European Union by September, and have signaled that the regulator is open to using injections targeting the variant. BA.1 older this fall, as those specifically targeting the newer subvariants are further behind in clinical development.

Rather, the US Food and Drug Administration (FDA) has said it will seek specific inclusion of Omicron’s new BA.4 and BA.5 branches in any new injection used in the country. Moderna, which signed a 1 billion pound ($1.2 billion) deal with the British government to build the country’s first mRNA vaccine facility earlier this year, said on Monday it expected further approvals for the adapted vaccine in Australia, Canada and the EU in the coming weeks.

Pfizer Inc and BioNTech have also been testing modified versions of their mRNA vaccine to combat the Omicron variants.

Meanwhile, Sanofi and its partner GSK are working on a protein-based vaccine that targets the Beta subvariant, which dominated for some time last year.

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