NHS Somerset said so far nearly 30% of over-80s and almost 50% of over-75s have not had the vaccine.
On average in the UK about 9,000 people over 75 become infected with RSV each year and have to be admitted to hospital, according to the NHS.
The RSV vaccine being used is new, and the lead for neighbourhoods and vaccinations in the county, Mike Kelly, said: “It can make a real difference to staying well over the winter months.”
This virus spreads easily through coughs and sneezes and can affect the lungs of older people harder than other age groups.
The vaccine is being offered to people aged 75-79, those who turned 80 years old after 1 September 2024, and pregnant women from 28 weeks onward – as it also protects newborn babies during their first months of life.
NHS Somerset said eligible patients should be being contacted by their GP to book the free vaccine.
