The U.K. will roll out an additional Covid vaccine shot for the elderly and its clinically vulnerable population, the country’s vaccines regulator announced on Monday.

Adults over the age of 75, nursing home residents and immunosuppressed over-12s will be given an extra dose of a Covid vaccine in the spring as a “precautionary strategy for 2022,” Britain’s Joint Committee on Vaccination and Immunisation said in a press release.

Over-18s will be offered the Pfizer-BioNTech or the Moderna Covid vaccine for their spring dose, while 12 to 18-year-olds will be given the Pfizer-BioNTech vaccine only.

An extra booster shot will be given 6 months after an eligible individual’s most recent dose, the JCVI said.

For older people in the U.K., this will be the fourth vaccine dose they have been offered. For people with a severely weakened immune system, it will be the fifth vaccine shot they have been offered. The bulk of the population has been offered three shots, two vaccinations and one booster.

The regulatory body noted in the release on Monday that “there remains considerable uncertainty with regards to the likelihood, timing and severity of any potential future wave of Covid-19 in the U.K.”

“There may be a transition period of a few years before a stable pattern, such as a regular seasonal wave of infection, is established,” the JCVI said.

Many of the U.K.’s oldest, and most vulnerable, adults received their most recent Covid vaccine in September or October. The JCVI noted that the immunity this group gained through their booster shot may wane substantially before the fall, when it plans to roll out a wider booster program.

Details on the fall program have not yet been publicized.

Of the eligible population in the U.K. — those aged 12 and over — 85% have been fully immunized with two doses of a Covid vaccine, and two-thirds have received a booster shot.

The JCVI’s announcement came as U.K. Prime Minister Boris Johnson prepares to announce an end to all remaining Covid restrictions in England, a move which has faced heavy criticism from medical professionals.

Many of England’s restrictions had already been lifted, but some — such as the legal requirement to self-isolate after testing positive for the virus — currently remain in place.

Johnson is also expected to announce on Monday that access to free Covid tests will be scaled back.

The U.K. recorded 25,696 new cases of the coronavirus on Sunday, with around 508 people per 100,000 people currently infected with the virus. Provisional data shows that there were 74 deaths in the U.K. due to Covid.

“Thanks to our COVID-19 vaccination rollout, we are already the freest country in Europe,” U.K. Health Secretary Sajid Javid said in a statement on Monday. “It has saved countless lives, reduced pressure on the [National Health Service] and is allowing us to learn to live with the virus.”