Some public health practitioners argued that those individual preventive services related to communicable diseases (e.g. immunisation, contact tracing, treatment for STIs) form part of public health practice because they help to protect the health of the whole population, through herd immunity and reducing the spread of infection. A minority argued that immunisation is only a legitimate part of public health activity when it is delivered as part of a publicly organised program, such as through local government or school health services. The corollary of this point of view is that immunisations performed in general practice are not a public health activity. Alternatively, it was argued that childhood immunisation in general practice is simply the implementation strategy for an organised national approach to immunisation, one which is supported by special payments to GP's and the Australian Childhood Immunisation Register, with follow-up of those parents who do not comply.