People 65 and over in England are being urged to get a top-up booster vaccine against Covid at a time when more people are coming into hospitals with the virus.
Those who are eligible can book via the NHS website, on the NHS app, or by calling 119.
The rollout has been brought forward as a precaution against a highly mutated new Covid variant called BA.2.86.
While hospital numbers are up, intensive care (ICU) ones are low.
Although the virus is mutating and changing, the vaccines still provide good protection against getting very sick with Covid, say experts.
How much Covid is there around?
Testing for Covid has been massively scaled back, making it difficult to know how many people in the UK might have it.
The continued rise in hospital rates over recent weeks suggests the virus is likely to be circulating more widely among the population.
Hospital admissions of patients testing positive for Covid are now at the highest rate since the end of April, at 4.6 per 100,000 people.
That is still below the level reached last winter – 11.8 per 100,000.
Rates remain highest among people aged 85 and over, followed by 75 to 84-year-olds.
Last autumn, all over-50s were offered a Covid booster, but the government’s advisers on vaccines recommended that only over-65s and other “vulnerable groups” should be included automatically this year.
For most people, catching Covid, while unpleasant, is less risky. Past Covid infections and vaccines have trained the immune system to stop severe illness, even if it cannot stop infection.
What is the new BA.2.86 Covid variant?
It is a spin-off of Omicron. From the data the UK gathers, it does not appear to have taken off in a big way yet. There have been 37 cases recorded so far in England, while Scotland has recorded five cases.
Experts are keeping a watch on it and say it is too early to make predictions or draw conclusions.
Steve Russell, NHS director for vaccinations and screening, said: “The new Covid variant presents a new risk, but NHS staff are rising to the challenge once more to do all they can to protect the public.
“Vaccines are our best protection against flu and Covid-19, and I strongly encourage all eligible people to come forward for their life-saving winter vaccines as soon as they can.”
Dr Gavin Dabrera, from the UK Health Security Agency, said there had been a continued increase in Covid cases in the past week. He added: “While hospital admissions have also continued to rise, ICU admissions remain low and stable. We will continue to monitor rates closely.”
GP practices and other local NHS services will also be contacting people to offer both flu and Covid vaccines, and people can book the flu vaccine by searching online for a local pharmacy.