Covid booster vaccines can be extended to those aged between 40 and 49 in the UK after being approved by the government’s vaccines watchdog, which also gave approval for teenagers aged 16 and 17 to receive second jabs. While such decisions are devolved, all devolved nations tend to accept JCVI guidance. Ministers in England, Scotland and Wales have already said they would extend boosters. The announcements, made in a virtual briefing by Prof Wei Shen Lim, the chair of the Joint Committee on Vaccination and Immunisation (JCVI), will be welcomed by ministers, who have been keen to extend vaccination programmes before winter. Immediately after the JCVI gave the green light for boosters for over-40s, the health secretary, Sajid Javid, said the advice had been accepted in England. “I have asked the NHS to prepare to offer those eligible a vaccine as soon as possible,” he said. The Scottish government said separately it would also extend its booster programme and allow 16- and 17-year-olds to receive a second dose. The move comes after a study by the UK Health Security Agency found that boosters gave more than 90% protection in people over 50. The research showed that two weeks after receiving a booster dose, protection against symptomatic infection was 93.1% in those who had initially received Oxford/AstraZeneca and 94.0% for Pfizer/BioNTech. Lim said it was possible boosters might be extended further down the age range. “It may well be that adults who are under 40 years might require a booster dose or a third dose at some point. We don’t know whether that is definitely the case yet. “We are looking very closely at the data all the time and should there be sufficient signal to warrant a third dose, so a booster dose for this age group, then certainly we will announce that and advise that accordingly.” Speaking at the same briefing as Lim, England’s deputy chief medical officer, Prof Jonathan Van-Tam, warned that even with the extension of boosters, intended to tackle potentially waning immunity from earlier jabs, winter could be a difficult time with Covid. He said: “People keep asking me about Christmas. I think for Christmas and the winter period, we can expect respiratory viruses to be around and we are particularly concerned that flu will come back and add to our problems, and it could be quite a bumpy few months ahead.” Speaking on a visit to a vaccine centre in east London on Monday morning, Boris Johnson also warned of a potential “blizzard” of infections over the winter, urging people to get boosters if eligible. “What we have certainly got to recognise is there is a storm of infection out there in parts of Europe, you can see those numbers ticking up very sharply in some of our continental friends,” the prime minister told reporters. “And we’ve just got to recognise that there is always a risk that a blizzard could come from the east again, as the months get colder.” Those currently eligible for a booster, which is usually given six months after the second dose, include those aged 50 or over, or anyone younger seen as clinically very vulnerable to Covid. Others who are eligible include frontline health and care workers, or those who care for someone at high risk from Covid. There is a separate programme of third jabs for people who have compromised immune system, for whom vaccines are often less effective. It was also announced that people aged 16 and 17 can receive a second Covid jab 12 weeks after their first. The JCVI decided in favour of first jabs for the age group in early August. But there had been no updates since, with some parents reporting that GPs were telling teenagers they would need to wait until they were 18 for their second dose. The JCVI is understood to have approved second jabs in outline last month but nothing had been formally announced. Ministers see the extension of boosters as a key element in efforts to mitigate the impact of Covid over the winter, with the number of jabs now picking up after as slow start. So far, 12m boosters had been given, with 2m in the last week, the Conservative party co-chair Oliver Dowden said. Among efforts to speed up the process, some people are being invited for boosters five months after their second jab, rather than six. Covid infection rates have fallen during November but they are rising again, and more than 1,000 deaths connected to the virus were recorded in the week to Sunday.