Every child in Scotland aged between two and 11 is to be offered the flu vaccine as a nationwide immunisation programme is rolled out.
The vaccine will be given as a nasal spray.
About 150,000 children aged two-five and about 400,000 primary school children will be eligible to receive it.
A campaign to inform parents about how their child can be vaccinated and the protection it can offer is under way.
Last year, every two and three-year-old and about 100,000 school children taking part in a pilot programme were offered the vaccine.
This is the next phase of a rollout that will eventually see all children aged two-17 covered. Health experts estimate this could prevent an additional 200 deaths a year and up to 1,100 hospitalisations.
'Quick and painless'
Dr Nicola Steedman, the Scottish government's senior medical officer, said: "Flu can be very unpleasant for children, and in some cases it can develop into more serious health complications such as bronchitis, pneumonia and middle ear infection.
"Parents can make sure their child is safeguarded against flu by taking up the offer of this free vaccine. It's safe, quick and painless, and offers protection against the types of virus that are most likely to be circulating this winter."
Parents of primary school children have been urged to look out for and return consent forms sent home in school bags so that their child can be vaccinated.
Parents of children aged 2-5 should make an appointment with their GP practice from October.
Health Secretary Alex Neil added: "The scale of this vaccination programme, once fully implemented, is unprecedented.
"Immunisation is the best way of protecting against serious diseases, and the childhood flu programme is about ensuring more people than ever in Scotland are protected from the flu virus."