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

USA - Treatment as Prevention

posted: 10/12/2009

The USA has joined the list of countries producing national statements about how effective HIV treatment can make passing on HIV during sex very unlikely. 

The USA statement uses much the same evidence as the earlier Swiss, French and German statements on HIV treatment as prevention that we have reported. However, it is a lot more cautious, urging continued consistent condom use.

"In summary, for couples in which one member is HIV-infected, treatment of the infected partner with effective ART and suppression of viral load to undetectable levels should greatly reduce the risk of transmission to the uninfected partner. However, this risk is not eliminated and it may not be maximally reduced at all times due to some of the factors discussed above. Moreover, the likelihood of transmission may be expected to increase with repeated exposures over time."

"In a model which estimated transmission risk in the setting of suppressed viral load (<50 copies/mL) without intercurrent STIs, the number of expected transmission events occurring within a population of 10,000 serodiscordant couples over 10 years was estimated to be 215 for female-to-male transmission, 425 for male-to-female transmission, and 3,524 for male-to male transmissions [31]."

"In a meta-analysis of data from 11 cohorts including 5,021 heterosexual couples observed no transmissions among persons receiving ART with a viral load of <400 copies/mL; however, analysis of the data was compatible with the possibility of one event per 70 person-years [32]. For this reason, it is important that individual couples recognize the risk, and use additional preventive methods (e.g., condoms) in order to further minimize the chance of transmission."

So they advise condoms for heterosexual couples to prevent a 1 in 70 person years possibility of transmission.

This statement and advice comes from the US Centers for Disease Control.

Effective HIV treatment where the viral load is undetectable reduces the risk of HIV transmission but some slight risk remains. The risk is higher for gay men than most heterosexual people, and sexually transmitted infections especially raise the risk of transmission.

US Centers for Disease Control statement Effect of Antiretroviral Therapy on Risk of Sexual Transmission of HIV Infection and Superinfection [read on webpage] OR download it as a pdf

French statement

German statement

Swiss statement

French - Treatment as Prevention

posted: 13/05/2009

The Swiss, the Germans, and now the French have all recently issued ‘treatment as prevention’ statements. The French statement recommends campaigning about the benefits of HIV testing and treatment, and advises against using compulsory testing.

The idea of using HIV treatment as a means of prevention implies a major shift in the way HIV treatment is regarded, a statement issued last month by the French National AIDS Council said.

The statement on 'The appropriateness of treatment as an innovative tool for fighting the epidemic of HIV infections' first details the mathematical models and studies showing that having more people on treatment could considerably reduce HIV transmission.

One study was the British Columbia mathematical model, which demonstrated that achieving an undetectable viral load in more than 50% of the HIV-positive population should result in a slow decline in HIV prevalence.

The authors of the French statement point out that even in the good conditions of France, in which 72% of people with HIV are diagnosed, 85% of those are on treatment, and about 74% are undetectable, only 46% of the total HIV-positive population has undetectable viral load (the proportion in the UK is about 43%). Higher rates of testing and diagnosis, starting treatment earlier, and more treatment success will all be needed for treatment to make a really significant contribution to prevention.

French recommendations
The statement therefore recommends:

• Campaigning by both public health departments and voluntary organisations to increase awareness of the benefits of HIV testing and early treatment
• Normalising regular HIV screening among at-risk people
• De-emphasising negative or outdated messages about the toxicity and pill burden of antiretrovirals
• Training physicians to offer treatment outside CD4 criteria to HIV patients who have difficulty in maintaining safer sex.

Cautions and concerns
The paper largely rejects the idea that telling people that if they have an undetectable viral load reduces HIV transmission might increase risk-taking, and so raise, rather than reduce, transmission rates. It points out that studies have shown that people who know their status and take treatment generally take fewer sexual transmission risks than people who do not know they have HIV.

Swiss statement rejected

It explicitly rejects the Swiss Statement of January 2008, which said that within certain tightly defined criteria, HIV-positive people with an undetectable viral load “do not” transmit HIV.

The French say: “[Study] Results will not…identify a specific plasma viral load threshold below which the risk of transmission would be null.” It recommends that health messages should provide information on the reduction in sexual transmission risk offered by treatments, “while indicating that a residual risk may remain”. The Swiss were emphatic - if you fitted their criteria, there is no transmission risk. Most experts don't quite go that far - like the French here, they say there is a slight risk.

Another positive burden

It raises concerns that where previously it has been possible to frame HIV prevention as an activity shared by seropositive and negative people alike, using antiretrovirals as the sole means of prevention would imply that the HIV-positive partner “wholly bears the responsibility to contain the risk for the other”.

No compulsory testing

It cautions against any element of coercion being introduced into HIV testing and treatment, warning that “it could be tempting to consider population-compulsory systematic screening and to voice a more or less insistent summons for the treatment of persons identified as HIV-positive”. Instead it recommends that screening should be more systematically offered.

Keep pushing condoms

It also urges the continued promotion of condoms on the basis that they remain “a reliable means enabling everyone, without knowing the serological status of their partners, to keep control of protecting themselves and others during sexual intercourse”. It adds that “entering treatment, knowing that it needs to be followed lifelong…is not a minor decision and may never be so”.

Positive messages
However the statement's tone is primarily optimistic, with a new, hopeful message about HIV treatment. In particular, it says that public health communications “should break with strategies that have hitherto implicitly focused on the drawbacks of treatment…as arguments to convince the general uninfected population to keep safe”.

It says that “reducing transmission risk through treatment is a powerful reason for seropositive persons to rest assured. It should allow them…to live their sexuality in a more peaceful and radiant way”.

Undiagnosed: get yourself tested

Regarding HIV-negative people, it adds that treatment as prevention imposes “a new form of responsibility…on all sexually active persons to know their serological status through periodic screening and to resort to treatment in the case of...diagnoses.”

Treatment can reduce stigma

It ends by hoping that treatment as prevention may help reduce the stigma against HIV. Despite the deep roots of HIV stigma, it says that “the public spread of…the observation that transmission risk is reduced in treated persons may contribute to [normalising] the idea that infected persons are no danger when they accept their status and follow treatment”. Treatment as prevention, it says, may be one way of “restoring the dignity of people living with HIV”.

The French language statement was published on 9 April and the English version is here.

Source and reference