The health system includes the totality of actions that society and the State undertake in relation to health. The health system may be defined as an organized social response to the health problems of a specific population (Frenk, 1997). Thus defined, all countries have a health system. The system may be more or less organized. Its impact on the health situation of the population may be greater or lesser, but as long as there is an institutional response - whether public or private-it may be said that some health system is available.

Health insurance is a specific form of health system. There are typical configurations of health systems, i.e., forms of organization that tend to be repeated, where the different actors involved assume characteristic roles. Health insurance systems appear more and more in the countries of the Americas as legitimate and efficient solutions to configure an organized social response to the health needs of the population.

Health insurance is a system to protect people against the contingency of illness. The state of knowledge of the health sciences will probably allow the development of insurance capable of truly guaranteeing the health of its beneficiary population. Insurance, however, tends to limit its functions to guarantee access to goods (drugs, prosthesis, orthesis, etc.) and services (care at the first, second and third level) that allow them to maintain or recover health. Insurance is an institutional arrangement that involves risk management, dilutes individual risks of illness in group risks and tends to establish a logic of solidarity in its financing.

There are various models of health insurance. It might be considered that there exists a continuum of alternatives in health insurance organization. The extremes stretch from private, for-profit organizations to social security organizations financed with public resources (Table 2). Between these extremes, however, is a wide number of alternative arrangements that include, for example, private, non-profit insurance companies and public insurance plans that compete in the ambience of managed competition. In conclusion, insurance may be classified in different ways and the specialized literature has developed diverse classifications of health insurance plan systems and social security.²⁸ Below is one of these classifications, selected because it facilitates consideration of the problematic situation of medicines in insurance systems.

^28. Outstanding among more recent works on the subject are: Fleury Teixeira (1992), Mesa-Lago (1992), Freylejer (1995), Starfield (1996), Frenk (1997), Frenk and Londonio (1997), Miranda Radic (1994), Filgueira and Martínez (1999) and Maceira (1996).

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