The U.K. government has signed an advance purchase deal with CSL Seqirus for more than 100 million doses of flu vaccines in the event of a future outbreak.

Britain has the right to buy the vaccines, produced at CSL’s plant in Liverpool, if the World Health Organization declares a flu pandemic, the U.K. Health Security Agency said in a statement September 26.

The deal ensures that the U.K. will be able to “get jabs into arms fast regardless of global demand and save thousands of lives,” Maria Caulfield, vaccines minster for the agency, said.

The U.K. was at the forefront of COVID-19 vaccination efforts in late 2020 and early 2021 thanks to early access deals and rapid regulatory clearance of shots. While that saved many lives in the country, it also caused tensions across Europe over access to shots. Public health experts have criticized rich countries for being too slow to make vaccines available to the developing world during the COVID pandemic.

Flu pandemics can arise when a new influenza strain emerges against which people have no immunity. There have been three such events over the past century, in 1957, 1968 and 2009. The 1918 flu pandemic caused more than 50 million deaths globally, according to the statement.

CSL Seqirus is a unit of Australia’s CSL Ltd and has partnered with the British government in the past for pandemic flu vaccines, it said in a separate statement.