Britain's health regulatory agency on Wednesday approved the country's first COVID-19 booster targeting two Omicron sub-variants.

The Medicines and Healthcare Products Regulatory Agency (MHRA) said that it approved a booster vaccine from Pfizer and BioNTech to help prevent Omicron BA.4 and BA.5 sub-variants infections.

A 3D printed Pfizer logo is placed near medicines from the same manufacturer in this illustration

"All approved COVID booster vaccines help to improve the protection obtained from earlier doses of the vaccine and help give longer-term protection against getting seriously ill from COVID-19," the agency said.

There are more than 300 Omicron sub-variants, hundreds of which, continue to infect the population. Pfizer and BioNTech said the approved booster produced a strong antibody response after one month. The U.S. approved their latest vaccine last month.

The FDA's Dr. Peter Marks said that booster shots and vaccination "remain the most effective measure to prevent the severe consequences of COVID-19, including hospitalization and death."

The two-part booster shot is approved for people 12 years and older.