Mathematical Model Predicts That Widespread Antiretroviral Use Could Halt Worldwide Spread of HIV in 50 Years
The worldwide HIV/AIDS epidemic could be slowed or "even eradicated" after 50 years of "widespread" use of antiretroviral drugs, according to a new mathematical model, Newsday reports. The model was developed by University of California-Los Angeles researchers and is published in today's issue of the Lancet Infectious Diseases. Using a mathematical method called "uncertainty analysis," the researchers calculated the impact of a range of variables on HIV infection in San Francisco. The researchers assumed that antiretroviral treatments lower the amount of virus contained in the bloodstream by at least half and possibly up to 100-fold, meaning that widespread antiretroviral use will make it more difficult for HIV-positive individuals to transmit the virus to sexual partners. The mathematicians also assumed that drug-resistant strains of HIV will develop but will be less infectious. Even when "worst-case assumptions" -- such as the evolution of drug-resistant HIV that is infectious and an increase in unprotected sexual activity among people using antiretroviral drugs -- are factored in, the model predicts that antiretroviral treatment will stop the HIV/AIDS epidemic in San Francisco "well before" the end of the century.
But Will It Work?
Mathematician Stephen Gange of Johns Hopkins University School of Medicine said he would not be in favor of crafting public policy on the basis of a mathematical model, adding, "I think we all want to see the epidemic decrease, but using math models to get us there is stretching things a bit." Gange said that other studies conducted in Uganda and the United States have shown that antiretroviral treatment "only marginally affects a person's ability to infect" others with HIV. He added that the main reason that antiretroviral treatment will not slow the epidemic is that "in the real world, most patients manage to sustain a 50% or less reduction" in viral load, a smaller reduction than calculated in the UCLA study. UCLA mathematician and study co-author Sally Blower replied that her model is based on San Francisco data, where most patients on antiretroviral therapy have experienced decreases in viral loads of more than 50%. But she added that the pandemic could only be slowed through widespread antiretroviral use because treating only a small percentage of the HIV-positive population would have "very little impact" on HIV transmission. The researchers concluded that regardless of whether antiretroviral drugs can reverse the HIV/AIDS pandemic, the drugs "should be available to all who need them, regardless of poverty," because they help extend life expectancy (Garrett, Newsday, 7/31).