Dame Sally Owens says it is crucial two to four-year-old children get flu vaccination Vaccine offered to children in 2012 after severe outbreak lead to deathsÂ Parents urged to sign children up to stop them infecting family membersÂ Â Jab made available to pregnant women, NHS staff, and those over 65 Last year the nasal flu vaccine was offered to two and three year olds. It has been extended to four-year-olds this year, but only a quarter have had it Parents must take their young children to have the flu vaccine because they are â€˜super-spreadersâ€™ of the virus, according to the chief medical officer. Dame Sally Davies said that so far this year, only a quarter of children aged two to four have been vaccinated even though all are eligible. She warned that it was crucial they are protected as they are vulnerable themselves and may pass it on to elderly relatives or pregnant mums. Last year was the first time that all two and three year olds were offered the vaccine and from this autumn, it has been extended to four year olds.Â But uptake is considerably lower this year and fewer than a third of the two million children in this age group have been vaccinated. It is administered as a nasal spray containing a tiny amount of the virus which is enough to make the body immune. Dame Sally said: â€˜Flu can be really nasty for toddlers, leading to time off nursery which has a big impact on mums and dads and sometimes even a stay in hospital.Â They also spread the virus easily and often pass flu to grandparents and other relatives who can become very ill, fast. â€˜Giving two, three and four year olds the free nasal spray really is in everyoneâ€™s interests if you want to help avoid a miserable winter for all the family.â€™ NHS figures yesterday showed that flu rates across the UK are currently low, although they have just started to rise slightly.Â Yet there have been no precise statistics for England only since the beginning of October because of â€˜data qualityâ€™ issues. The flu jab is also offered for free to pregnant women, the over 65s, front-line NHS staff and anyone with an underlying health problem.Â But in 2012 the Government agreed to extend it to the under-fives following a particularly severe flu outbreak which claimed the lives of several previously healthy children. Next year, they plan to offer it to all five and six year olds at school and eventually it will be available to all children under 16. Scientists advising the Government have calculated that even only vaccinating half of children under four for flu would prevent half a million cases. Young children are known as â€˜super-spreadersâ€™ amongst medical professionals as they come into close contact with friends, donâ€™t wash their hands or cover their mouths when coughing. Dame Sally Owens, Britain's chief medical officer, is urging more parents to take their children to be vaccinated in an effort to stop the spread of flu this winter Officials are particularly concerned they may spread it on to elderly relatives who may develop bronchitis and pneumonia. Figures show that patients with an underlying health problem such as heart disease or asthma are 11 times more likely to die from flu. Since September, when the immunisation campaign began, only 29 per cent of two year olds have had the vaccination compared with 34 per cent last year. The uptake in three year olds is broadly similar and this is the first year four year olds have been offered the treatment. But the Department of Health said that half of mothers were not aware the vaccine existed or that their children were eligible. Others may also be wary of side-effects. The vaccine contains a weakened form of the flu virus but experts insist it is safe.Â Manufacturers say one in ten children tend to suffer from side-effects which include a runny nose and headaches. Children with egg allergies or asthma cannot have the spray as it may trigger reactions. Instead they are advised to have a standard jab.Â Experts say the spray works far better in children with fewer side-effects. The jab can cause a very mild bout of flu. Children have been dubbed 'super-spreaders' because they often pass the illness to other family members, including grandparents who can become very ill