The NHS is reminding millions of people who have still not had their booster this week to book in, with more than four million people sent a second reminder.

NHS England has said that a further 200,000 invitations been sent to people newly-eligible for their top-up dose, with letters encouraging them to come forward and book their appointment.

Reminders come as health bosses urge those who are considered overdue for their booster to get jabbed, with new research from UK Health Security Agency shows that since mid-December 2021 boosters have prevented around 105,000 hospitalisations for coronavirus in those aged 25 years and over.

There are more than 1.5 million appointments available over the next seven days and 3,000 sites across the country offering vaccines, including 1,000 walk-in sites.

Dr Emily Lawson, NHS vaccination lead, said: “More than four in five eligible people aged 16 and over are double jabbed and over half have already taken up the offer of a booster, with tens of thousands still coming forward every day.

“However, NHS data shows that millions of people are overdue their booster by at least six weeks – four million people have not come forward for their top-up since they received reminders from the NHS in December – and while some had to delay because of a coronavirus infection it is still absolutely crucial that people get their booster in order to increase their protection against reinfection and the dangers of long Covid.

“It is important we don’t lose sight of the fact that Covid is still a very serious illness that is affecting thousands of people’s lives every day, with new research showing the risk of death involving Covid-19 is 93% lower for those who have had a booster or third dose compared to those who are unvaccinated so please book in for your vaccine today.”