(USA TODAY) -- In a broad new expansion of HIV screening, an influential government panel now says everyone ages 15 to 65 should be tested for the virus that causes AIDS.

The draft recommendation, issued Monday by the U.S. Preventive Services Task Force, is far broader than its last one in 2005, which called for screening only those at high risk.

"We need to find the people who are infected and get them on therapy," says John Bartlett, a professor at the Johns Hopkins School of Public Health in Baltimore who wasn't involved in the new guidelines.

The task force's decision also could help people afford testing, says Carl Schmid, deputy executive director of the Washington, D.C.-based AIDS Institute, an advocacy group.

Insurance companies sometimes make their payment decisions using grades issued by the task force. The group said its recommendation is based on grade-A-level evidence, the highest grade possibility, because of a "high certainty" of benefit. Under the Affordable Care Act, private insurers must cover all services that get a grade of A or B without co-pays. Patients can opt out of testing.

Although the Centers for Disease Control and Prevention has recommended routine HIV testing for adolescents and adults ages 13 to 64 since 2006, relatively few doctors routinely test patients today for HIV.

Only about half of adults have been tested, Bartlett says. And 20% of those with HIV don't know it.

The task force's recommendation could have a greater influence than the CDC's long-standing advice, Bartlett says, because these guidelines are aimed at primary care doctors rather than the small number of specialists who treat AIDS.

The task force was influenced by new research showing the substantial health benefits of treating patients early in the course of infection, says task force chairwoman Virginia Moyer, a pediatrician at Texas Children's Hospital in Houston. She says doctors had lacked evidence that treating people early made a major difference.

Also, a landmark study published last year found that giving people anti-AIDS drugs reduces their ability to spread the infection by 96%, which led doctors to talk of "treatment as prevention."

Other research shows that people who know they have HIV reduce risky behavior such as sharing needles or having unprotected sex by 25%, says Helen Koenig, an assistant professor of infectious disease at the University of Pennsylvania.

Many HIV patients learn their diagnosis only after being infected for years, the task force says. About one-third of newly diagnosed people with HIV progress to AIDS within a year of diagnosis, suggesting they could have carried the virus for a decade.

Moyer says she hopes routine HIV screening will reduce the stigma of testing, so patients don't feel singled out, and also encourage doctors. About 20% to 25% of people with HIV have no clear risk factors, such as intravenous drug use or gay sex.

"There really needs to be a lot of testing in people who don't think they're at risk," Bartlett says.

Carlos del Rio, a professor at the Emory School of Public Health in Atlanta, says he hopes primary care providers quickly add HIV testing to their routine.

"We're not very good as clinicians at figuring out who is infected," del Rio says. "A lot of doctors are still uncomfortable with HIV. People say, 'People in my community do not have HIV.'"

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