The Department of Health announced this week that healthy children aged between six months and five years are to become the second priority group for the vaccine.

But NHS Northamptonshire bosses said yesterday that parents of the estimated 44,000 healthy under-fives in the county will not be contacted until the first phase of vaccinations for high risk people is over and sufficient vaccine is available for their children.

They said the speed at which the youngsters get the jabs will depend on the availability of vaccines and people to deliver them.

Dr Olufunke Adedeji, public health consultant responsible for implementing the vaccination programme in Northamptonshire, asked for understanding from parents.

He said: "Our top priority at the moment is to complete the delivery of the first phase of the vaccination programme to some 140,000 high risk patients, some of whom will be vulnerable children and frontline health and social care staff.

"These are people who are at high risk of severe complications if they catch the virus or are at risk of spreading the virus to vulnerable people."

NHS Northamptonshire revealed yesterday that it currently does not have enough doses to deliver the first vaccination phase and the Department of Health is still finalising arrangements with the British Medical Association and other health bodies on how the second phase will be delivered.

Dr Adedeji said: "Completion of phase one is dependent on our receiving sufficient vaccines and so far we have had 51,000 vaccines delivered, and the promise of 33,000 more next week.

"We will let parents of healthy children know as soon as we can offer them the vaccine."

Health bosses said parents can protect their children in the meantime with frequent hand-washing and by making sure they use tissues for coughs and sneezes in line with the 'Catch It, Bin It, Kill It' advice.