http://whqlibdoc.who.int/hq/2001/who_v&b_01.07.pdf

Ensuring access to essential immunization services is the responsibility of the government. Basic health services, including immunization, are a human right.Essential immunization services should be provided at no charge in order to maintain equitable distribution of these essential services, to combat poverty and to meet public health goals that capture the positive externalities of immunization (herd effect). Public financing of essential immunization services should cover the full costs so that informal user fees or in-kind charges can be eliminated.