Only 43 per cent of two and three-year-olds in Bath and North East Somerset are protected against the potentially-dangerous winter flu virus.
Parents of young children are now being urged to bring their sons or daughters forward to get vaccinated as quickly as possible.
The flu vaccine for two and three-year-olds is given as a pain-free nasal spray, and can be had at most GP practices and community pharmacies.
Gill May, Chief Nurse, Bath and North East Somerset, Swindon and Wiltshire Integrated Care Board, said: “It is massively important that we look out for the youngest members of our communities, not only for their own wellbeing but also to prevent them from passing on their illnesses to others.
“This year’s flu season is expected to be particularly challenging, especially for very young children, many of whom will not have built up any natural immunity, following the national lockdowns that prevented families and friends from mixing.
“The child flu vaccine is the best form of protection against this nasty seasonal illness, which can cause some very real problems, such as bronchitis and pneumonia, and is so much more than the average winter cold.”
All children aged either two or three years old are eligible to have the flu vaccine for free.
Older children, such as those in primary and secondary education, are also eligible for a free flu vaccine and, in most cases, these vaccinations will be given during school time.
Although very young children cannot have the Covid-19 vaccine, all those aged five and over are encouraged to do so.
Parents can arrange to have their child vaccinated against Covid-19 at a range of venues across the region, including Bath Racecourse
Many GP practices and community pharmacies also offer a Covid-19 vaccination service.