The PARTNER study examines the risk of transmitting HIV when taking treatment (ART).

The second phase of the study, PARTNER 2, is now under way. It is currently enrolling male couples where one partner is HIV positive and the other negative. The positive partner will be taking ART to reduce virus in their body.


What is it about?

PARTNER2 is enrolling gay male couples. One partner will be HIV positive on medication and the other HIV negative. The study examines risks of HIV transmission when someone is taking effective HIV treatment.

What will the study involve?

On a 4-6 monthly basis you and your partner will be asked to:

  • Complete a questionnaire on sexual behaviour (both partners)
  • Have an HIV test (negative partner)

Who can take part?

You and your partner are eligible to take part in the study if:

  • One is an HIV positive man on treatment and the other an HIV negative man
  • You’ve had anal sex together without a condom in the last month
  • You expect to have sex together again in the coming months

PARTNER 2011-2014


PARTNER was designed as an observational study estimating risk of HIV transmission. It observes couples with different HIV status who inconsistently use condoms. The positive partner will be taking effective ART medication.


Phase 1 results from PARTNER were reported in the Journal of the American Medical Association in July 2016. These included findings for heterosexual and gay couples. Results showed no transmissions when the positive partner’s viral load was under 200 copies/mL. PARTNER2 is continuing with the enrolment and follow-up of solely gay male couples.