What can modeling tell us about the threat of antiviral drug resistance?

PURPOSE OF REVIEW Currently, antiviral resistance is a major public health concern. Here, we review how mathematical models have been used to provide insights into the emerging threat of antiviral resistance. We focus mainly on the problem of drug resistance to HIV. RECENT FINDINGS We review how antiviral models of HIV have been used: (1) to understand the evolution of an epidemic of drug-resistant HIV, (2) to predict the incidence and prevalence of drug-resistant HIV, (3) to conduct biological 'cost-benefit' analyses, and(4) to make public health policy recommendations. We also briefly discuss antiviral resistance for HSV-2 and influenza. Recent studies indicate that for HSV-2 and influenza drug resistance is not likely to become a major public health problem. However, for HIV the situation is very different. Results from several studies predict that a high prevalence of drug-resistant HIV will be an inevitable consequence of more widespread usage of antiretroviral therapies (ART). However more widespread usage of ART will save a substantial number of lives, and could even result in epidemic eradication. SUMMARY Models have been used in many ways to provide insight into the emerging threat of antiviral resistance, particularly for HIV. At this stage in the HIV epidemic the most important future use of models may be that they will force the goals of public health policies to be clearly defined. Once goals have been defined it can then be decided whether a high prevalence of drug-resistant HIV is a threat or simply a justified means to an end.