The agency has adopted the widely accepted position that an HIV-positive person with an undetectable viral load cannot pass the virus through unprotected sex.

If you can’t detect it, you can’t transmit it.

Federal officials are finally on board with that message when it comes to HIV.

The Centers for Disease Control and Prevention (CDC) have announced that they concur with scientific evidence asserting that when an individual has an undetectable HIV viral count, there’s effectively no risk of them transmitting HIV to a sexual partner.

The CDC is following the lead of more than 400 international groups that signed a consensus statement in 2016 recognizing that “undetectable = untransmittable” (U=U).

The CDC wrote, “When ART results in viral suppression, defined as less than 200 copies/ml or undetectable levels, it prevents sexual HIV transmission.”

“Across three different studies, including thousands of couples and many thousand acts of sex without a condom or pre-exposure prophylaxis (PrEP), no HIV transmissions to an HIV-negative partner were observed when the HIV-positive person was virally suppressed,” the CDC letter stated. “This means that people who take ART daily as prescribed and achieve and maintain an undetectable viral load have effectively no risk of sexually transmitting the virus to an HIV-negative partner.”

The CDC’s announcement came last week on National Gay Men’s HIV/AIDS Awareness Day.

“We’re thrilled that the CDC has endorsed what we and many other HIV/AIDS organizations, researchers, and doctors have known for many years: if you’re HIV positive with an undetectable viral load, there is a negligible risk of HIV transmission,” said Eric Sawyer, vice president of public affairs and policy at Gay Men’s Health Crisis (GMHC), an HIV and AIDS prevention, care, and advocacy organization.

Negligible means the risk is so small statistically that it’s not worth considering.

In 2016, two studies, published in The New England Journal of Medicine and The Journal of the American Medical Association (JAMA), tracked couples in which one partner was HIV-positive and one partner was not.

Both studies found that after the HIV-positive partner was on antiretroviral therapy (ART) for at least six months, there were zero transmissions of HIV to their partner during sex without condoms.

Additional research presented at the 2017 International AIDS Society (IAS) Conference in Paris bolstered these findings.

Doctors put people diagnosed with HIV on ART immediately, even if their viral loads are low.

Doing so helps prevent the spread of HIV.

The technique is referred to as “treatment as prevention.”

“Clinicians have known that treatment as prevention, when coupled with other prevention tools including condoms or PrEP, works and that it’s important to put a newly diagnosed person on antiretrovirals as soon as possible — not only for their health and to get their viral load under control, but also for the health of their potential partners,” Sawyer told Healthline.

“The CDC endorsement of U=U might help further convince newly diagnosed patients to follow this method, which would help us bring down overall incidence of HIV infection,” he continued.

Dr. Daniel Murrell, an infectious disease fellow at the University of Alabama at Birmingham who works in an HIV clinic, says that the invention of better therapies and a wider selection of ART drugs has made treating HIV easier than ever.

HIV clinics across the country vary regarding when, or if, they’ve started treating patients under the pretense of U=U.

But Murrell mentioned that, “Every clinic has been operating with the idea that your health must be optimized.”

“With patients I see that are undetectable, I’ll use this info about the CDC backing as a reinforcement,” Murrell told Healthline.

He explained that he’ll let his patients know “they’re doing a great job, aren’t putting their partner at risk, and will encourage them to keep taking their medicine.”

While studies show that HIV is not transmittable even without the use of condoms and PrEP, Murrell said that doctors will still encourage undetectable patients to practice safe sex.

“We’ll continue handing out condoms and PrEP therapy,” he said.

Gay and bisexual men are still affected by HIV. Among gay and bisexual men living with diagnosed HIV, 61 percent have achieved viral suppression.

That’s an improvement from past years, but the CDC noted it’s still “well short of where we want to be.”

Misinformation, stigma, and fear around HIV remains prevalent.

People diagnosed with HIV overestimate the risk of infecting their HIV-negative partner. Even though only 10 percent of participants in a recent survey had non-suppressed viral loads, a third of respondents believed their chance of infecting a partner was high, according to AIDSMAP.

“We hope the CDC’s endorsement of this fact helps lessen the stigma that still exists around people living with HIV, and that it encourages an open dialogue between sexual partners about their status, treatment, and prevention methods,” said Sawyer.

Prevention Access Campaign has been a leader in education around the issue with the U=U campaign.

Advocates also hope the CDC’s backing will provide additional leverage for challenging state nondisclosure laws, which criminalize HIV-positive people who don’t disclose their HIV status.

Sawyer pointed out, “The CDC’s acknowledgement is a further indication that our laws around nondisclosure are no longer supported by the current accepted science and research about HIV transmission.”