People with HIV who have an undetectable viral load as a result of antiretroviral therapy (ART) have a practically “zero” chance of transmitting the virus sexually, a European study has found.

In a finding that could dramatically change the lives of HIV-positive people and public health policies the world over, a study of 282 gay men on treatment with undetectable levels of the virus in their blood, found that none of them transmitted it to their partners through unprotected sex over one year.

While the final results of the study are due to be released in 2017, interim results from the first two years of the study show that no cases of HIV were transmitted either by anal or vaginal sex where the HIV-positive partner had an undetectable viral load (under 200 copies/ml).

The European researchers made the announcement last week at the Conference on Retroviruses and Opportunistic Infections in Boston, Massachusetts.

These findings throw a monkey wrench into the pseudo-scientific ramblings of adult business gossip-mongers such as Mike South and Rob Black, who have claimed without a shred of evidence that adult performer PCR testing is useless because an individual on antiretroviral drugs with an undetectable viral load could enter the performer pool and still infect other performers.

The research comes from the first two years of the PARTNER study which involves 1110 serodiscordant couples, where one partner is HIV-positive and the other is negative.

While the couples participating in the PARTNER study are a mix of both gay and straight, all the HIV-positive partners are on ART, a medicinal therapy which reduces traces of the HIV virus in the body to undetectable levels.

Statistical analysis shows that the maximum likely chance of transmission via anal sex from someone on successful HIV treatment was 1% a year for any anal sex and 4% for anal sex with ejaculation where the HIV-negative partner was receptive; but the researchers say the true likelihood is probably much nearer to zero than this.

The PARTNER study also boosted hopes that a strategy of ”treatment as prevention” could play a major role in stemming the spread of HIV.