Mail & Guardian Online - July 21, 2009
Mara Kardas-Nelson

Scientists and policy makers attending the conference are calling for a drastic increase in access to antiretroviral drugs, dubbing the "treatment as prevention" model a "strategy for the elimination of HIV transmission".

While Granich made clear the proposal is currently only a theoretical model, it is based on several pieces of evidence concerning transmission levels seen within patients on ART versus those who are not. Granich points to South Africa to demonstrate the model, where statistically each person living with HIV infects one other person every 1,25 years.

Since the current life expectancy after infection is 10 years, seven new infections occur for each initial person living with the virus. According to Granich, a person's viral load, or the amount of HIV detected in someone's body, is "the single greatest risk factor for HIV transmission". Since "ART can lower viral load to undetectable levels", it can also severely decrease transmission rates. Therefore, Granich claims, if every HIV-infected South African were to immediately begin treatment, the number of new infections would drop from seven to zero, eventually eliminating the virus.

Granich, a medical officer at the HIV/Aids department of the WHO, presented the findings of a theoretical model published in authoritative medical journal The Lancet earlier this year, which suggest that treating all people who test HIV positive immediately after their diagnosis could potentially nearly eradicate the virus by the year 2050.

Currently, WHO guidelines recommend that people living with HIV start treatment when their CD4 count, a measure of the strength of the immune system, drops below 350, which often occurs several years after initial infection and when a person may have developed Aids-defining illnesses.

This marker has been hotly debated in the past several years, however, with an increasing number of studies showing that early ART uptake leads to a decrease in rate of transmission. Granich claims that this model could result in a 95% reduction in new HIV cases within 10 years, with more than seven million lives saved. While the WHO has yet to change its treatment guidelines, a consultation on ART as prevention will take place in November this year to discuss possible implementation of the strategy.

"Treatment is also about prevention," Granich said

Julio Montaner, president of the International Aids Society (IAS), agreed: "The preventative value of ART is clear. Unless we treat people who are healthier, with higher CD4 counts, we will never get to the end."

Despite its potential benefits, there are financial and logistical concerns that could prevent the model from working, particularly the developing world, where there are high rates of infection. Because treatment cannot be initiated until someone's HIV status is known, the model requires that each person be tested for HIV yearly. However, worldwide only half the people living with the virus know their HIV status, and stigma and discrimination remain a barrier to voluntary testing.

Financial implications offer another potential barrier, especially in light of the economic downturn. While specific numbers have not yet been discussed, Granich claimed that while there would be a "heavy initial investment", the model would prove to be "cost-saving" in the long run.

The model's proponents argue that while individually the cost of providing a person with antiretroviral drugs is substantial, on a larger scale it is financially more conservative than waiting for a person's immune system to weaken, during which time that person may develop costly opportunistic infections, and during which time they are more likely to transmit the virus, creating a larger disease burden with a greater financial cost.

"By treating more, we're actually using a cost-cutting treatment," said Montaner. "The time to invest in ART is now."

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