بیماری ایدز و رشد اقتصادی: رویکرد سرمایه انسانی

Using a model that combines growth and health capital equations this study analyses the impact of HIV/AIDS on economic growth. The econometric results indicate that the epidemic's effects have been substantial; in Africa the marginal impact on income per capita of a 1% increase in HIV prevalence rate is minus 0.59%. Even in countries with lower HIV prevalence rates the marginal impacts are non-trivial. Hence while the human and social costs of the HIV/AIDS epidemic are major causes for concern, these results indicate that the macroeconomic affects of the HIV/AIDS epidemic are important.

“Twenty years after the first clinical evidence of acquired immunodeficiency syndrome was reported, AIDS has become the most devastating disease humankind has ever faced. Since the epidemic began, more than 60 million people have been infected with the virus. HIV/AIDS is now the leading cause of death in sub-Saharan Africa. Worldwide it is the fourth-biggest killer.” (UNAIDS/WHO, 2001). It is estimated that in 2003 about 5 million more people acquired the HIV virus and that more than 3 million people died from AIDS1 bringing total deaths from the epidemic to more than 25 million (UNAIDS, 2003). While the highest prevalence and death rates and number of infected persons are reported for sub-Saharan Africa, there is evidence that the epidemic is accelerating in Asia and Eastern Europe and that complacency is causing an upturn in prevalence in North America and Western Europe. Wherever the epidemic strikes it imposes severe human and social consequences. Family life is severely disrupted as adults are rendered less able and/or unable to work, health care costs rise and children are forced prematurely onto the labour market and/or made orphans. These human and social consequences of the epidemic, especially in sub-Saharan Africa, are increasingly visible as the media devotes resources to covering the epidemic. Over and above these consequences are the economic costs of the epidemic. These include immediate costs, such as increased health care expenditures and reduced labour productivity, and long-term costs, such as reduced levels of education, health, physical and social capital. Since few economists would doubt the potential of the AIDS epidemic to create substantial economic costs, it is surprising that there have been relatively few studies into the economic, especially the macroeconomic, implications of the epidemic (see below).2 In part this is probably a reflection of the limited recognition given to the impact of health upon macroeconomic performance and the relatively recent availability of data that allow systematic econometric evaluations of the epidemic. The results reported in this paper are based upon an augmented Solow model that incorporates both health and education capital. Importantly, the model is estimated as a system wherein health capital is partially determined by health status, in particular the prevalence of HIV infection, using panel data. The next section briefly reviews the literature on HIV/AIDS and development. Section 3 summarises the derivation of the growth and health capital equations, and comments on the panel data methods. Section 4 starts with a discussion of the available data and how they influence the specification of the estimating equations, and then reports the results. The results are discussed in Section 5 and the final section contains concluding comments.

The pronounced impact of HIV/AIDS prevalence on health capital/infant mortality, and hence on incomes, suggests that the epidemic may now be entering a stage where the loss of life is starting to impact appreciably upon both social and economic interactions. These results suggest that the seemingly comforting conclusion that excess labour supplies in many developing countries would be sufficient to ensure that the macroeconomic impacts of the HIV/AIDS epidemic might be relatively muted does not appear to be holding. However, there are difficulties with this type of broad brush analyses, especially the dependence of the model specification upon the presumption of steady state relationships. In particular the results indicate that there are substantial differences between regions, which point to the importance of a careful consideration of samples and sub-samples in order to gain a fuller picture of the relationship between HIV/AIDS and economic performance. Among the least satisfactory aspect of the results is the absence of significant coefficients on the education capital terms in the growth equations; while this is common in the literature it continues to be unsettling. The results also indicate the need for further explorations of how the epidemic impacts upon economic relationships, so as to direct policy makers' attention to the economic implications of AIDS. In the longer term it is argued that there is a need for research that provides a greater understanding of the mechanisms by which sustained epidemics impact upon economic performance. Such a research agenda will necessitate the development of forward looking models that provide insights into how, inter alia, the large numbers of AIDS orphans will impact upon the accumulation of education capital ( Bell et al., 2003, may provide a start for this type of research). Nevertheless, these results produce useful additional information and indicate that the macroeconomic affects of the HIV/AIDS epidemic are substantial. In the countries of the Africa sample, where HIV and malaria are health problems on a scale that OECD countries might regard as catastrophic, the level of the marginal impacts of HIV prevalence on income pre capita is of orders of magnitude that suggest that a substantial proportion of the apparently poor economic performance of many of these economies over the past 10 to 20 years can be attributable to the HIV epidemic; a characteristic that has been omitted from many macroeconometric studies that have sought to explain economic performance in many developing countries. Moreover the marginal effects are sufficiently large to suggest that they threaten macroeconomic stability, which is generally most fragile in the poorer countries that are also those most prone to catastrophic escalations of the epidemic. If the legitimate aspirations of the inhabitants of these countries are to be achieved and poverty reduction strategies, and similar policies, in these countries are to be realised, the maintenance of macroeconomic stability is likely to be a prerequisite. All of which indicates that over and above the humanitarian case for supporting healthcare provision and services in countries suffering from the HIV/AIDS pandemic, there is a strong case for providing more general economic support.