Two-thirds of two to three-year-olds are yet to be vaccinated against the flu this autumn.
NHS Hampshire and Isle of Wight are urging parents to get their little ones protected ahead of the October half-term.
Since September, more than 11,000 children have been vaccinated across Hampshire and the Isle of Wight, leaving two-thirds yet to be protected.
Dr Matt Nisbet, GP and vaccination lead for NHS Hampshire and Isle of Wight, said: "Having the vaccination protects your child against flu and serious complications such as bronchitis and pneumonia, which can develop from it."
The flu vaccine, a painless nasal spray, offers protection to children and helps reduce the spread of the virus.
Parents are encouraged to contact their GP practice to book their child's vaccination.
The Protect Your Little Monsters campaign, part of the autumn vaccination programme, aims to raise awareness during the half-term.
For more information, visit the NHS website.
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