HIV - Treat to prevent?

posted: 06/04/2010

The use of HIV treatment for preventing HIV is a hot – and controversial – topic. Now researchers are saying people with HIV should not stop using condoms and start depending on HIV treatment to protect their partner until you have taken treatment and the viral load has been undetectable for at least 12 months.

 
Some, perhaps most, people who are taking HIV treatment, who do not have sexually transmitted infections and who have an undetectable viral load, are not infectious to their sexual partners.

Some of the research suggests that taking HIV treatment and keeping an undetectable viral load is at least as good as using condoms in preventing HIV. Not everyone agrees, and there are heated debates about this at HIV conferences.
 

The debates started about two years ago with what is now called the Swiss statement - it was followed by broadly similar statements from France, Germany and the USA.

Reliably undetectable?
Danish researchers wanted to see if people taking HIV treatment can rely on their viral load remaining undetectable. They looked at the viral load results of every person in Denmark who was taking HIV treatment. Research shows that HIV transmissions are very rare if a person had a viral load below 1000 copies/ml. So they assumed that everyone taking HIV treatment with a viral load above this is potentially infectious. They then calculated the amount of time that people taking HIV treatment had an ‘infectious’ viral load of above 1000.
 

Reliable for most

For people who reached an undetectable viral load, it stayed undetectable 99.5% of the time.
But during the first year of HIV treatment, viral load can suddenly increase to detectable levels – this happens for about 5% of the time. People won't know when their viral load has taken an upward, detectable, blip when HIV transmission becomes more likely.

The risk of transmission was especially high during the first six months of HIV therapy, when 8% of the time was spent with a viral load above 1000 copies/ml. During the next six months, viral load was at potentially infectious levels for a little over 1% of the time. After the first year viral load was only above the potentially infectious threshold for an average of 0.6% of the follow-up period. After five years, only 0.03% of the follow-up period was above 1000 copies.

Different routes of transmission do not seem to make a difference - except for injecting drug users who had a potentially infectious level of viral load 1.5% of the time. The researchers belive this is because of poorer treatment-taking among injecting drug users.

Wait until viral load stays undetectable for 12 months

They therefore think that the Swiss recommendation about using treatment for HIV prevention should be tightened. They believe people should not swop condoms for treatment until there has been an undetectable viral load for at least twelve months, twice as long as suggested in the Swiss statement.
 

Sexual Transmitted Infections and viral load

Sexually transmitted infections can cause undetectable viral loads to suddenly become detectable - especially in the genital fluids. We measure all our viral load samples from the blood but what passes on HIV is HIV in the genital fluids. Many people have undetectable HIV in the blood but can have a detectable viral load in the genital fluids - and these are the ones that transmit HIV in sex. Sexually transmitted infections cause detectable genital viral loads and make us more infectious. Some experts say that among groups of people with high rates of sexually transmitted infections, such as gay and bi men with HIV, undetectable viral load is too unreliable to judge your risk of passing on HIV.

Swiss reminder

The debate on treatment as prevention was kick-started a little over two years ago by the release of what is known as ‘the Swiss statement.’
Senior Swiss HIV doctors and researchers said that HIV-positive individuals who were taking HIV treatment were not infectious to their sexual partners if:

• Their viral load had been undetectable for at least six months.
• They took their HIV treatment properly.
• They did not have any sexually transmitted infections.

Source

image from the HIV Prevention Justice Alliance blog

Call for Treatment as Prevention

posted: 10/03/2009

Pioneers in HIV research now call for testing of a strategy that uses treatment-as-prevention deserves testing out.

One of the pioneers of HIV research, former Harvard retrovirology professor William Haseltine, said today that universal testing and treatment now offers the best hope of controlling the HIV pandemic.

Writing in the news magazine The Atlantic, Haseltine said that three other authorities involved in the discovery of HIV – Robert Gallo, Max Essex and Robert Redfield – have reached the same conclusion.

“History has shown that epidemics can be controlled, even in the absence of a vaccine,” he says. “Both syphilis and tuberculosis were pandemic at the end of the nineteenth century, and both epidemics were controlled by effective diagnosis and treatment.”

Global call for new treatment-as-prevention strategy

“I recommend that WHO, PEPFAR and the Global Fund begin studies to assess the effectiveness of universal testing and early treatment for the prevention of HIV transmission,” he urges.

Vaccines doubts

At a recent seminar on global governance challenges at the James Martin 21st Century School at Oxford University, Professor Jonathan Weber of London’s Imperial College said that after 27 years in HIV research, he no longer believes a vaccine to be achievable. Instead he believes that population-based antiretroviral therapy (PopART) is the only strategy currently available that holds out the prospect of HIV eradication.

WHO - S Africa and UK

Population-based treatment, or maximising the numbers testing and on treatment, is a subject of growing interest to researchers. Last November the World Health Organization published details of a mathematical modelling exercise which suggested that if all people in South Africa could be diagnosed and begin antiretroviral treatment within a year of infection, the number of new infections could be reduced by 95% within ten years. It also looked at its use in the UK.

Montreal conference calls

Then at the Sixteenth Conference on Retroviruses and Opportunistic Infections in Montreal, Canada earlier this month, two studies of transmission risk in HIV-discordant couples were presented. One showed no cases of transmission in couples where the HIV-positive partner took antiretrovirals, while the other showed an 80% reduction in transmission risk.

Christophe Fraser, an epidemiologist from Imperial College, London, warned the confererence that the striking effect of universal treatment in mathematical models might not be replicated in real life if it proved less than 99% effective, and called for careful examination of the assumptions in the WHO models by other epidemiologists before policy is made.

Brighton CHAPS conference calls

And the recent UK gay men's sexual health conference CHAPS, in Brighton debated this. George House Trust's policy expert Chris Morley was one of a panel of speakers debating Treatment as Prevention.

Many people with HIV on treatment with an undetectable viral load are already rethinking condom use and telling partners. There are still some risks of HIV transmission - particularly if either partner has a sexually transmitted infection. But in ideal circumstances, it is pretty clear that the transmission risks with an undetectable viral load are not much worse than with using condoms consistently. People have a right to know the facts and to choose how to manage transmission risks and disclosure to suit themselves.  

Source

Undetectable But Infectious?

posted: 10/02/2009

One of the hottest topics over the last twelve months has been the infectiousness (or otherwise) of people taking HIV treatment who have an undetectable viral load in their blood.
 

The debate was kick-started a year ago by what’s come to be known as the “Swiss Statement”. This said that individuals taking HIV treatment who had an undetectable viral load and no sexually transmitted infections were essentially non-infectious to their partner in a monogamous heterosexual relationship.
 

The authors of the Swiss Statement noted that effective HIV treatment suppressed viral load to undetectable levels in both blood and semen.
However, two studies presented to the CROI Conference in Montreal, Canada, have confirmed that HIV can be undetectable in blood, but still detectable in semen in a minority of men, even without any STIs.
 

1 in 7 "undetectable" men have detectable and infectious semen

A Canadian study involving 25 men found that undetectable viral load in the blood, was found with detectable virus in about 1 in 7 semen samples. The virus in semen was potentially infectious.
 

Semen virus sometimes blips and becomes detectable

The study also showed that viral load in semen occasionally “blipped” to detectable levels.
About a third of men who’d been taking long-term HIV treatment that suppressed viral load to undetectable levels in the blood occasionally had detectable HIV in their semen.

A larger French study looked at paired blood and semen samples from 145 men taking HIV treatment. Viral load was undetectable in 85% of these paired samples. But in 3% of samples, HIV was undetectable in blood and detectable in semen – viral load in these samples ranged between 250 and 1200 copies/ml.
Most of these detectable samples were “blips”, and the French researchers found good levels of anti-HIV drugs in the patients’ semen.
 

There was discussion about the implications of these findings, in particular if the levels of HIV found in semen involved a significant risk of HIV transmission. There was only one case of HIV transmission in the French study, but this involved a patient who wasn’t taking his treatment properly.
 

Swiss should not claim undetectable people can never transmit

However, both sets of researchers concluded that an undetectable viral load in blood doesn’t always mean that viral load is undetectable in semen, and that successful HIV treatment doesn’t entirely eliminate the risk of HIV transmission. So the Swiss statement was a bit too dogmatic - transmission is possible but seems really unlikely.

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