San Francisco public health doctors are urging patients to begin taking HIV medications soon after their diagnosis rather than waiting until their immune systems become compromised, The New York Times reports. The city's Department of Public Health will announce the new testing guidelines this week.

According to the article, the policy shift was prompted by evidence that patients who start antiretroviral treatment earlier are more likely to live longer and less likely to develop illnesses—such as heart disease, kidney failure and cancer—that are common among long-term survivors. A recent study in The New England Journal of Medicine found that patients who put off therapy until their immune system started failing had a nearly twofold greater risk of dying—from any cause—than those who began treatment when their CD4 counts were above 500.

Under San Francisco's new policy, doctors will offer patients combination therapy and advise them to pursue early treatment, but the patients will ultimately decide whether to begin therapy right after their diagnosis.

“The history of HIV disease has always been about change,” said Diane V. Havlir, MD, chief of the HIV/AIDS division at San Francisco General Hospital. “We pride ourselves on working quickly with new data.”

Health experts also argue that early treatment will curb new infections by reducing viral loads in HIV-positive San Franciscans and thereby reducing their risk of transmitting the virus to their negative partners.

“I do anticipate it will drive down the rates of new infections,” said Mitchell H. Katz, MD, the city's director of public health. “It's a nice, secondary benefit of this new policy.”

Others experts argue that while newer HIV medications are less toxic than earlier regimens, the long-term effects of these new drugs remain unknown.

Jay Levy, MD, a San Francisco virologist with the University of California, was one of the first to discover HIV. He's skeptical of the city's new policy.

As he told the Times: “It's just too risky.”