I plan to give all 3 of my children the combined vaccine, wil be receiving it myself and administering it to all of my patients.
The individual vaccines are considered very safe, with the most common side effects being fever, brief flu-like symptoms, pain/redness/swelling at the injection site and fussiness. The only benefit to giving them combined is only needing one injection per vaccine session, for 1st time toddlers, 2 vaccines are required over a month time course.
Of course, I work with immunocompromised patients on a regular basis, so any chance to reduce me getting flu and exposing my patients to it is well worth it.
Vaccinating your children against the flu is a decision each person needs to make. Most people that get H1N1 or seasonal flu will be fine, but a small proportion of otherwise healthy people go on to become signficantly ill with some requiring intensive care and even dying from it.
It's a no brainer for children with asthma or other medical conditions, as they have a higher incidence of severe infections or asthma exacerbations.
People are contagious before having overt symptoms of the flu, so by the time one of the day-care children shows symptoms there is a good chance your child was already exposed. So, unless your child never leaves your home I think it's a good idea to get them vaccinated. (If your child never leaves the home there is another problem entirely.

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There is also the live flu vaccine which is not a shot - there is a possibility of getting the flu from the vaccine, albeit small.
Sorry to give a quick response to this - I've had a busy day.