HIV treatment as prevention - AIDS Conference 2012

Dr Josephine Birungi, who presented the recent findings from Uganda. 

©IAS/Moreno Maggi

There’s a lot of excitement about the use of HIV treatment as prevention. Results of a large randomised trial (HPTN 052) presented to the International AIDS Society conference in Rome last year showed that effective treatment reduced the risk of transmission by 96% in monogamous heterosexual couples.

But a much smaller study presented to the International AIDS Conference in Washington has revealed the potential limitations of treatment as prevention in ‘real-world’ settings. Its results would suggest that treatment doesn’t have any real impact on the risk of transmission.

The study was conducted in Uganda and involved approximately 600 heterosexual couples in long-term relationships, where one partner was HIV positive and the other HIV negative. HIV transmission rates were compared between couples where the positive partner was taking treatment and couples where treatment wasn’t being used.

The couples were followed for approximately two years.

Annual HIV incidence was approximately 3% in couples where HIV treatment wasn’t being used, compared to 2% in those where the positive partner was on treatment.

Viral load was tested after transmission took place. All the participants not on HIV treatment had a viral load over 1000. Thirty-five per cent of the people on treatment who apparently transmitted HIV had a viral load above this level.

The researchers who conducted the study emphasised that they are not questioning the impact of HIV treatment on infectiousness. However, they think its effectiveness as a prevention tool can be undermined by social, biological and cultural factors.

For instance, they found that transmission was more likely to occur in polygamous relationships. Nor did the researchers have any information on the prevalence of other sexually transmitted infections, which can increase the risk of HIV transmission.