By Lisa Rapaport

(Reuters Health) – A growing number of sexual minority men understand that HIV can’t be transmitted by people with undetectable viral levels, but a new study suggests men living with HIV have a better grasp of the facts than men who don’t have the virus.

Researchers surveyed 111,747 men who don’t identify as heterosexual about their sexual behaviors, condom use, drug use, HIV status and understanding of the HIV transmission risk. Overall, about 53% knew HIV could not be transmitted by individuals with undetectable viral levels – so little virus in their blood that it can’t be found with lab tests.

Almost 84% of HIV-positive men understood that undetectable effectively means untransmittable, compared with 54% of HIV-negative men, according to the report in JAIDS: Journal of Acquired Immune Deficiency Syndromes.

The findings suggest there’s more work to be done to educate people about HIV prevention, said lead study author H. Jonathon Rendina, an assistant professor of psychology at Hunter College in New York City.

Misunderstanding the facts may lead some people to choose riskier partners or behaviors, Rendina said by email.

“First, people who incorrectly assume sex with undetectable partners is risky are more likely to seek out HIV-negative partners, but a person in the early stages of infection who has not yet been diagnosed has extremely high viremia and is the greatest risk of transmission, so there is a false sense of risk reduction in serosorting,” Rendina said.

“Second, higher levels of HIV stigma are associated with reduced engagement in both HIV prevention and care, both of which exacerbate transmission rates (they make people less likely to get tested and make people living with HIV less engaged in care, thus less likely to remain undetectable),” Rendina added.

The simple message “U=U,” or undetectable equals untransmittable, is a powerful tool to encourage people living with HIV to take their medication and reach and maintain undetectable viral levels, Rendina said.

Although there’s no cure for HIV, the virus can become undetectable when there are too few copies of it in the blood to show up on standard blood tests. But copies can increase again if people stop taking antiviral medications.

“The U=U message can be transformative,” said Julia Marcus, an assistant professor at Harvard Medical School and Harvard Pilgrim Health Care Institute in Boston, who wasn’t involved in the study.

“It allows people with HIV and their partners to have sex… without fear of transmitting HIV, it breaks down stigma by changing the way people with HIV are seen by others, as well as how they see themselves, and it also encourages people with HIV to stay on treatment to keep themselves healthy and their partners HIV-free,” Marcus said by email.

One limitation of the study is that researchers only captured participants’ knowledge of HIV transmission at a single point in time, making it impossible to determine whether individual participants became more or less familiar with HIV transmission as time passed, the study team notes. Researchers did, however, see an increase in the proportion of participants who correctly answered questions about viral levels and transmission from the start of the study to the end.

Knowledge may increase over time as more people find less stigma associated with HIV status or sexual identity, Marcus said.

“Healthcare providers need to be crystal clear about the U=U message, regardless of any personal judgments they might have about their patients choosing to have condomless sex,” Marcus added. “An undetectable viral load doesn’t prevent unwanted pregnancy or other sexually transmitted infections, so providers should counsel patients about other sexual and reproductive health options available to them, including contraception, condoms and sexually transmitted infection screening.”

SOURCE: JAIDS: Journal of Acquired Immune Deficiency Syndromes, online December 5, 2019.