Prime Minister Boris Johnson said the jab milestone was “amazing” as he warned boosters will be crucial to keep people protected through the winter.

Meanwhile, the chief medical adviser at the UK Health Security Agency said the number of deaths among the vaccinated population is on the rise.

The prime minister tweeted: “An amazing 10 million people across the UK have already come forward for their booster.

“We know vaccine immunity wanes over time, so boosters are vital in keeping you and your loved ones protected through the winter.

“Please get this lifesaving jab as soon as you are called.”

In total, 10,062,704 people in the UK have received a top-up jab, according to the government, with 409,663 receiving one on Saturday.

But about 30 per cent of over-80s and 40 per cent of over-50s in England are yet to receive a booster shot of vaccine, the Department of Health and Social Care said.

People over 50 and those most at risk from COVID-19 are eligible for a booster six months after their second jab.

From Monday, the NHS is changing the booking system to allow people to pre-book a booster appointment five months after their second COVID-19 vaccine, allowing them to get it as soon as they pass the six-month mark.

The latest figures come as chief medical adviser at the UK Health Security Agency, Dr Susan Hopkins, said elderly and vulnerable people who are double vaccinated have started dying, as the immunity provided by the vaccine reduces over time.

“We’re still seeing deaths in mainly the unvaccinated population, but increasingly, because of immune waning effects, there are deaths in the vaccinated group as well,” she said.

“It is particularly the older age groups, so the over-70s in particular, but also those who are clinically vulnerable, extremely vulnerable, and have underlying medical conditions.”

-with AAP