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.

How PARTNER2 relates to the original PARTNER study

The PARTNER study is an observational study recruiting gay and straight couples. It focuses on risk of sexual HIV transmission when the positive person is on treatment. Participating couples are not using condoms regularly when they enter the study. Some couples never use condoms. Though the study encourages condom use, it does not aim to change sexual behaviour.

To be eligible for the study, the positive person must be on treatment when enrolling. The study also wants to understand reasons why couples do not use condoms. Data is collected via participant questionnaires every 4-6 months.

Phase 1 results were reported in the Journal of the American Medical Association in July 2016. They showed 1166 serodifferent couples took part in the study. 888 couples met all the study criteria to have their data included. Two thirds of couples (548 couples) were heterosexual and 340 were MSM [38.3%]. During follow-up, the couples reported many condomless sex acts. MSM couples reported approximately 22,000 sex acts without a condom, heterosexual couples reported 36,000.

Whilst 11 HIV negative partners became positive during follow up, no infections were linked to the positive partner in the enrolled couple. Analysis of the viral genetics indicated it had been acquired from a different partner.

What is PARTNER2?

Phase 1 results from PARTNER are very important. However they only included 328 gay couples who practiced anal sex. PARTNER2 is a new phase of the study. It runs from 2014-2018 recruiting only gay male couples. This means the final results will be more precise for gay men. The results will help individual decisions on condom use. They will also help sexual health and HIV services provide information and advice to couples.

Why is PARTNER2 important?

PARTNER2 will provide additional evidence to have better confidence assessing anal sex risk. This data will inform potential scale up of ART for prevention purposes. This will be particularly important for MSM, trans women and others having anal sex.

How many gay male couples are needed?

We need to enrol another 450 couples, taking the total to approximately 950.

Who can participate in PARTNER2?

HIV+ men on treatment, who have had condomless sex in the last six months with a negative man. Men enrol with their partners if they anticipate having unprotected sex again in the future.

How many follow up years are needed to estimate transmission risk in anal sex?

We need 2082 person years of follow-up for similar confidence levels as the vaginal sex data.

Why is the gay male couple data so important?

Gay men need data on actual risk from anal sex. A risk assumed to be similar to vaginal sex is not sufficient. Data will also have major public health consequences. This is especially important for areas where anal sex is a major transmission route. Additionally, it will inform treatment programmes designed to reduce onward transmission.

To join the study or for further information please contact:

Tina Bruun, European coordinator: email- Tina.Bruun.01@regionh.dk

Tom Robinson, UK research assistant: email- tom.robinson2@nhs.net