Okay, the following is My Humble Opinion, based on what I just read about flu and CP by googling, coupled with my professional experience. Please discuss it with your pediatrician.
Although there are children with cerebral pasly (CP) and epilepsy who have only minor disability, when I think of "cerebral palsy and developmental delay" the image that comes to mind is a severely handicapped child who is non-verbal, incontinent, wheelchair dependent, and possibly dependent on a feeding tube, and/or a tracheostomy tube. These kids are VERY at risk for pneumonia, which is what it seems this flu sometimes causes at a higher rate than "normal" flu. Because of their inability to let their parents know they aren't feeling well, it's hard to catch things early and their immobility makes it more likely that any virus can turn into pneumonia, or set them up for a secondary bacterial infection.
I do not think autism causes any deficits in respiratory function or mobility, although I know it can interfere with communication. I don't think it would put a child at higher risk for flu complications than any other child. However, I do not specialize in autism and I am truthfully unaware if they are iummunocompromised, although I honestly do not believe they are.
In other words, I don't think your child's risk is any higher, or any lower, than any other school-aged child out there. I'd be more worried about a child with asthma or other pre-existing respiratory problems. But again, I don't know your child's individual history and I have no business telling you "for sure" he's not at higher risk. IMHO, if your son is able to tell you when he feels sick, and able to comply with your instructions to not touch his face or eat anything unless he's washed his hands, then I wouldn't worry about H1N1 any more than I would if he were not autistic. (btw, I'm not confident in ANY child's ability to follow the hand-hygiene guidelines, so yes, I do worry some about my own children, but all I can do is preach handwashing, send Lysol to school, and pray.

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