Did it work? We are not aware of any systematic studies comparing information strategies in the SARS infected countries and their potential effects on public risk perceptions, on public behavior and on ultimate economic and epidemiological outcomes, which would in any case be a complex statistical undertaking, given the many and subtle mutual interdependencies at work. Exhibit 2 above showed that the proportion of people in Singapore who thought it very or somewhat likely that they would get infected was less than half that in Hong Kong. However that may only reflect the fact that the attack rate of the disease was also much lower in Singapore than in Hong Kong. More research is clearly needed.

# **5.  Final Remarks**

This paper looks at some lessons about the economic impacts of infectious diseases suggested by the SARS epidemic of 2003, the Surat plague outbreak of 1994 and other similar events. The distinctive feature of these episodes is that although they ultimately result in relatively little illness and death, they entail large economic costs which are primarily the result of excessive preventive behavior by individuals and (on occasion) governments. The paper suggests that recent work in economic epidemiology may provide a natural framework for analyzing SARS/Surat type events, where preventive costs predominate, diseases like HIV-AIDS, where the costs of illness and death predominate, as well as diseases like pandemic influenza, where both types of cost could be very high. A particularly valuable feature of this approach is the central attention it gives to the behavioral choices made by individuals as a key variable in the epidemiology and dynamics of infectious disease. Such a focus also naturally draws attention to the subjective judgments of probability on which individuals base their decisions, and to the psychological, informational and social influences that shape such judgments. The possibility of economically costly biases and errors in individuals’ subjective judgments about disease suggest a potentially important role for public information and risk communication strategies. But account also needs to be taken of the incentives for governments to be transparent (or otherwise) in risk communications. The growth of mass communications technologies in non-official hands (cell phones, internet etc) appears to increase incentives for official honesty.

While the paper has pointed to recent work in different areas of economics that helps provide a more coherent conceptual framework for analyzing the economic impacts of infectious diseases, it also makes apparent the need for much more detailed and disease-specific research on the key relationships between disease biology, epidemiology and behavioral choice. An important research priority is to gain a better understanding of the types and intensity of prevalence elastic responses for different diseases, and of how they vary according to the transmission mechanism, virulence and other biological characteristics of the disease, the availability of information about the disease, the quality of medical and public health resources that are available, the general level of economic development, and so on. We need in particular to better understand how people gather information, form their perceptions of risk and make decisions in the high stress environment of an infectious disease outbreak. Public opinion surveys taken during SARS provide tantalizing glimpses of public perceptions at these times, but such 22