The UK government's Joint Committee on Vaccination and Immunisation has recommended all healthy adults in their 40s should be offered a booster jab for COVID-19, six months after their second dose.
It comes as England’s deputy chief medical officer, Professor Jonathan Van Tam warned: "We are in for some potentially difficult months over the winter. We're at a very unpredictable point in the epidemiology, the modelling is becoming very difficult. I regard it as still a time of great delicacy."
The number of people testing positive for the virus has jumped by six percent in the last week to 262,419 and there have been 1,093 deaths.
On Monday, 15 November, Professor Van Tam said if the vaccination booster plan went well Britain should be in “much calmer set of waters by the middle of spring."
But he added: "This virus is unpredictable. We are still very early on after it emerged in humans, and there are still many more lessons to learn."
Professor Van Tam said the government and the NHS was having to be "constantly vigilant" and warned people to continue to wear masks in situations where they might be in close contact with strangers.
Around 12.6 million people in Britain have received a third jab, mainly those aged over 50.
The JCVI also said it would be offering a second dose of the Pfizer/BioNTech jab to those aged 16 and 17.
Cabinet minister Oliver Dowden was upbeat when he appeared on Sky News, telling them: "There are no plans to stop Christmas happening. The huge difference this time is the vaccine. It is in our hands. If you get the booster when the call comes, that is the biggest wall of defence that we have against Covid."