Health problems near a modern hospital

[Robertoajr]

Why my city's got health problems near a modern hospital, if this hospital is not in overflow?

[Russishgao]

It's a game mechanic that not let you relax. Even if your districts in area of medical influence, you still need to call ambulance for sometimes, when epidemic starts in random place. Influence area just gives you opportunity to call a medical brigade to sources of desiase and don't let your people sick to the death, and the bigger area the better. Same for police and firefighters.