In my humble opinion, the majority of health issues directly relate to what the child has been through, their understanding of their situation and inner coping mechanisms, relationship with their birth family, and support from the foster family, as well as friendship network and school. It is unique for each child's experiences so needs a tailored approach.
Looked after children can develop health issues as a direct result of the above, i.e. bed wetting, night terrors, eating issues, self harm, OCD, lack of personal hygiene. These are less about health and more about having a coping strategy or outlet for unresolved trauma that brought the child into care.
Good luck. Any help is good help but you are looking at a BIG issue here that goes deep.
All children need dental care, eye care, vaccinations, treatment for general ills like flu, tummy bugs or verrucas etc (looked after or not) but the issues of looked after children are in addition and different to these and are linked to mental and emotional health.
That is just what I feel. No offence intended.