Swiss HIV/AIDS Statement Could Have Serious Ramifications

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Main Category: HIV / AIDS
Also Included In: Sexual Health / STDs;  Women's Health / Gynecology
Article Date: 26 Jul 2008 - 0:00 PDT

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If a recent statement released by the Swiss Federal Commission for HIV/AIDS (SFCHA) is misused, a study released on July 25, 2008 in The Lancet indicates that HIV incidence could potentially quadruple over the next ten years.

The SFHCA statement was released at the beginning of 2008, and stated that HIV positive people who are receiving effective antiretroviral treatment, defined by an HIV RNA level less than 40 copies per mL, cannot transmit the disease to an HIV-negative partner via unprotected sexual contact. The statement gives hope to those who fear transmission in situations when the risk is extremely small, and thus could have special significance in certain situations, such as an applicable couple attempting to conceive. The authors of the Lancet study point out, although the actual risk may be very low, it is also very unlikely to be zero.

To investigate the potential rammifications of such a statement, Dr David Wilson, National Centre in HIV Epidemiology and Clinical Research, University of New South Wales, Sydney, NSW, Australia, and colleagues implemented a simple mathematical model to estimate the cumulative risk of HIV transmission from effectively treated HIV-infected patients (assuming HIV RNA less than 10 copies per mL) to their HIV-negative partners over a long period of time. The risk of unprotected sexual exposure was explored in this situation, both for single acts and over a long period of time.

Assuming that each year, each couple has 100 unprotected sexual encounters, the cumulative probability of transmission is:

• 0.22% for female-to-male transmission,
• 0.43% for male-to-female transmission, 
• 4.3% for male-to-male transmission.

For example, in a population of 10,000 partnerships initially discordant for HIV, after ten years the expected number of HIV infections would be 215 from female-to-male transmissions, 425 from male-to-female transmissions, and 3,524 from male-to-male transmission. This new population would indicate an incidence rate four times current rates, when condoms are encouraged.

The authors are critical of the statement put out by the SFHCA: "On the basis of the data presented here, we believe that the Swiss statement is not a sensible public-health message because its logical outcome would be the abandonment of condoms by people with effectively treated HIV infection...As a population strategy, treatment as prevention has the potential to reduce HIV epidemics only if consistent condom use is maintained. Indeed, our analysis suggests that there is large potential for more harm than good." They additionally highlight a recent increase in infections of populations of men who have sex with men since effective treatment became available.

The authors conclude that the statement was misleading and provide their own description: Our analyses suggest that the risk of HIV transmission in heterosexual partnerships in the presence of effective treatment is low but non-zero and that the transmission risk in male homosexual partnerships is high over repeated exposures. If the claim of non-infectiousness in effectively treated patients was widely accepted, and condom use subsequently declined, then there is the potential for substantial increases in HIV incidence."

Professor Geoffrey P Garnett, Imperial College London, UK, and Professor Brian Gazzard, Chelsea and Westminster Hospital, London, UK contributed an accompanying comment in which they point out other benefits of regular condom use: "In many ways the Swiss statement provides the opportunity for positive public-health messages, by promoting adherence to treatment and concern over other sexually transmitted infections. The use of condoms, in addition to antiretrovirals, to further reduce risk and prevent other sexually transmitted infections can then also be promoted."

Relation between HIV viral load and infectiousness: a model-based analysis
David P Wilson, Matthew G Law, Andrew E Grulich, David A Cooper, John M Kaldor
Lancet 2008; 372: 314-20
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Written by Anna Sophia McKenney
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