Treatment as Prevention

Treatment as prevention (TasP) refers to using antiretroviral treatment (ART) to suppress the amount of HIV virus in a person’s blood to a level so low that it cannot be detected by regular testing methods. This is referred to as an undetectable viral load. There is solid evidence that a person with an undetectable viral load cannot transmit HIV to their sexual partners.

Based on research from studies around the world including HIV Prevention Trial Network (HPTN 052), Opposites Attract, and the Swiss Statement, couples in heterosexual and same-sex relationships in which one person was HIV positive and the other was HIV negative did not transmit the virus to their partners if the HIV positive partner had a undetectable viral load. In the most recent study, PARTNER, there were zero transmissions out of 58,000 condomless sex acts between people with HIV with undetectable viral loads and their partners who are HIV negative.

A person living with HIV who has an undetectable viral load cannot transmit HIV to their sexual partners if they meet the following conditions:

  • they have been on antiretroviral therapy (ART) for six months;
  • they have an ongoing undetectable viral load and;
  • they take their medication as directed by their doctor. It is important that they do not miss doses of their medication and that they attend regular appointments with their HIV doctor.

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