Q: How can one partner test positive and the other test negative?

A: It is quite common for one partner to test positive and the other negative, even if they have been having sex without condoms.

Mostly this is explained by luck and the role of other risk factors. Over time, most people will catch HIV if they continue to be at risk.

Even though the negative partner has been exposed and not infected, they can still catch HIV in the future.

Now you both know your HIV status you can still stay together and have sex safely.

The negative partner could use PrEP to reduce the risk to close to zero. This is a great way to protect your health.

Or if the positive partner has an undetectable viral load on treatment, the transmission risk also gets close to zero.

The PARTNER study showed this for both vaginal and anal sex and in gay and straight couples. There were no linked HIV transmissions after couples had sex more than 58,000 times without condoms..

You can also stay safe and prevent infection by using condoms when having sex and not sharing needles or blood products with your partner.

Even when STIs might have increased the HIV risk, there were no linked transmissions in the PARTNER study.

1 June 2016