According to the definition of the W.H.O. constitution
"Health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity and not merely the absence of disease of infirmity."
.." Therefore, Health Informatics is processing any information related to Human Well-Being as:
a) Physical: Medical Care; Diseases causes, preventions and treatments.
b) Mental: Philosophy, Education and Psychology
c) Social: Politics, Economy and Environment