The priorities for antiviral drug resistance surveillance and research.

The number of available antiviral drugs is growing fast. The emergence of drug-resistant viruses is well documented as a cause for drug failure. Such viruses also carry the potential for transmission, the risks for which vary according to specific viral transmission dynamics. This potential is best described for HIV and influenza. Resistance to the new generation of hepatitis C virus inhibitors is also likely to become a cause for concern. The priorities for future action to limit resistance include application of sophisticated surveillance mechanisms linked to detailed virological data, development of optimal treatment regimens (e.g. combination therapies) to limit emergence of resistance, and a focus on prevention strategies to prevent transmission.