Drs. Katz and Gerberding [1] argue effectively for prophylaxis after sexual exposures to HIV. As a physician who treats many occupational HIV exposures, I offer a few comments.

Many patients seeking prophylaxis after sexual exposures are likely to present to emergency departments for care because populations with sexually transmitted diseases often use this facility for episodic care. Because sexual exposures often occur after normal office hours, a public health campaign emphasizing rapid postexposure treatment and attempts to provide treatment within hours rather than days (as is recommended after occupational exposures [2, 3]) would increase use of emergency departments.

In the emergency department, our experience has been that occupational HIV exposures are best managed with well-defined protocols and resources, including 24-hour on-call availability of experienced physicians to provide consistent counseling and treatment decisions. Prophylaxis is further facilitated with "starter packs" of antiretroviral drugs and streamlined follow-up care. These methods are clearly achievable, but they are resource-intensive, expensive, and unlikely to be in place for most patients with nonoccupational exposures. These new patients will be less knowledgeable and require more time for meaningful counseling, particularly in addressing partner risk assessment and the probability of ongoing exposures to minimize futile treatment and its associated hazards. Additional emergency department issues include following up HIV test results and ensuring appropriate follow-up care for a transient population. When ready access to primary care or public health providers is not available, emergency departments may well be the most viable sites for preventive treatment of HIV. Practice guidelines for sexual exposures will, however, be extremely difficult to follow without an adequate infrastructure for counseling, treatment, and follow-up.

Finally, the cost-effectiveness analysis presented in Katz and Gerberding's paper clearly supports timely preventive treatment for patients with high-risk sexual exposures. It does not provide guidance for the more common situation in which source partners are inaccessible and less than 50% of them are likely to be HIV infected.