HIV-positive men who are on treatment that makes the virus undetectable do not transmit HIV to their partners, according to new study from the Kirby Institute at the University of New South Wales (UNSW) in Australia.

From 2012 to 2016, the study regularly checked in with 358 serodiscordant gay male couples (where one has HIV and the other does not) from Thailand, Brazil and Australia. During that time, the researchers recorded nearly 17,000 acts of condom-free anal sex, and none of those acts resulted in the transmission of HIV.

HIV, the virus that causes AIDS BSIP/UIG Via Getty Images

On Tuesday, the findings of the study, titled "Opposites Attract," were presented at the International Aids Society (IAS) Conference on HIV Science in Paris.

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"Our research adds to the evidence from a small number of other international studies of heterosexual and homosexual couples and means that we can say, with confidence, that effectively treated HIV blocks transmission in couples of differing HIV status," Andrew Grulich, the study's chief investigator and a professor at the Kirby Institute, said in a statement.

Related: Child Born With HIV Now Free of Infection

Kevin Robert Frost, the CEO of amfAR, one of the organizations that funded the study, found the results encouraging.

"As HIV continues to disproportionately affect gay men and other men who have sex with men worldwide, the results of this study are extremely encouraging and underscore the need to get people tested and onto treatment immediately if they are HIV positive," Frost said in a statement. "This important breakthrough underscores yet again how investments in HIV research yield invaluable dividends in the global response to HIV.”

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