HOUSTON — In his State of the Union address, President Trump surprised Congress by asking for a “commitment to eliminate the H.I.V. epidemic in the United States within 10 years.” I’m a physician who specializes in H.I.V. and AIDS prevention in a city with one of the highest infection rates in the country, so that’s music to my ears. But the president needs to know that we’re going to fail if we don’t start working much harder.

After nearly 40 years, we finally have the biomedical tools and the public health strategies to end the H.I.V. epidemic in America. The winning strategy goes like this: Increase the number of people who get tested for H.I.V., and start those who test positive on antiretroviral therapy as soon as possible, which helps prevent transmission of the virus. Those who test negative but are vulnerable to infection because of sexual activity should take pre-exposure prophylaxis, or PrEP, the daily drug regimen that reduces the risk of getting H.I.V.

The tragedy is that those tools are sitting on the shelf in many parts of the country, especially the South, where H.I.V. rates are still rising among some groups and where AIDS disproportionately afflicts African-Americans. Just this week the Centers for Disease Control and Prevention reported that the “progress in H.I.V. prevention has stalled.”

Big cities on both coasts — where AIDS was concentrated when it was officially recognized as a health condition in the early 1980s — have deftly managed the disease. San Francisco was once ground zero, yet in 2017 new H.I.V. diagnoses there fell to 221, a record low. The city’s Department of Public Health credits PrEP and a rapid-start program that gets those who test positive for H.I.V. into care within five days.