A bold and strategic shift in the way HIV drugs are used could reduce the global prevalence of the virus 70-fold in the foreseeable future, according to a Canadian researcher.
The controversial tactic would involve the expansion of access to triple-drug therapy to all people infected with the human immunodeficiency virus that causes AIDS, as an essential component of international prevention strategies. The idea is hinged on mounting evidence that transmission of the virus is significantly reduced when there is little of it circulating in an infected person's bloodstream. Current drug treatments, if used effectively, can bring the viral load down to these undetectable levels.
Dr. Julio Montaner, director of the B.C. Centre for Excellence in HIV/AIDS and lead author of the article published in today's issue of The Lancet, said that the high incidence of HIV worldwide is not likely to change in the near future for a number of reasons: The prevention strategies currently in place are only partially effective; a preventative vaccine has yet to be developed; and current treatment strategies are not enough to eradicate HIV infection. This makes finding ways to expand access to HIV drugs, formally known as highly active antiretroviral therapy, or HAART for short, that much more significant, he said.
"The status quo is no longer acceptable," said Dr. Montaner, who will become the president-elect of the International AIDS Society at the end of this month's International AIDS Conference in Toronto, where he is presenting these findings in his plenary address.Traditionally, HIV drugs are only given to patients with some degree of immune dysfunction related to the virus, what Dr. Montaner calls a "patient-centred approach." But the past decade has seen great improvements in simplifying the programs, reducing toxicities and side effects, and increasing effectiveness. Dr. Montaner and his colleagues are proposing to "change the paradigm" of treatment.
"Currently, you treat based on patients' needs, but . . . you could move into an area where you treat because the patient needs it, but also because it's good for society."
His theory is simple: New HIV infections can be transmitted only by someone who has the virus. If those people are given access to the antiretroviral therapy to reduce viral loads to undetectable levels, the virus is essentially put into quarantine and stops its transmission. So, even if infected people engage in high-risk behaviour, such as unprotected sex, they are still unlikely to spread the virus to others.
"[In North America] within 20 to 30 years, you could see HIV extinguishing itself and even possibly disappearing," Dr. Montaner said.
His report is based on an ecological study in Taiwan, which showed new HIV infections decreased 53 per cent after the introduction of free access to a HAART drug cocktail. He found similar results in British Columbia, where new infections fell by about 50 per cent from 1995 to 1998, and have remained unchanged to the present.
But critics call the idea unrealistic.
"The proposal is flawed at its core because it would require the testing and identification of all HIV-infected people worldwide, which is wholly unachievable and impossible, particularly in countries where stigma is high, and women in particular would be risking physical violence if they were identified as being HIV-infected," said Dr. Philip Berger, chief of the family and community medicine department at St. Michael's Hospital in Toronto.
Dr. Berger, one of Canada's leading AIDS experts, said that it is already proving difficult to get the necessary drugs out to those who desperately need them in sub-Saharan Africa, where last year's treatment targets were not met.
Dr. Montaner, however, does preface his hypothesis by admitting further trials need to be conducted before it is recommended internationally. He is in the process of expanding the program in British Columbia.
"We must stress that we do not see HAART as a replacement for strengthening of the prevention effort, but rather as an essential part of it," he said.
Traditionally, HAART has been deemed cost-effective when treating individual patients. Dr. Montaner said that his strategy would save more money in the long run because there would be fewer new infections.
Dr. Charles Carpenter, director of the Lifespan/Tufts/Brown Center for AIDS Research in Rhode Island, said that if further controlled trials show that the approach actually is effective in moderately developed countries such as Brazil, or even highly developed countries, then it will certainly be cost-effective in sub-Saharan Africa. "It's not like a magic bullet, but if we can truly decrease the incidence by 50 per cent, that is groundbreaking. These trials suggest that it can be done," he said.
Dr. Montaner said it's actually more expensive to delay treating people with HIV: "What we're doing is generating a larger pool of people who are infected, who are not treated, who have high viral loads, who carry on through life having a greater opportunity to transmit HIV."
Antiretroviral therapy in British Columbia last year, for example, is estimated to have averted 400 new infections, a savings of $96.4-million (U.S.) in lifetime treatment expenditures. About 4,000 people took the drugs in B.C. in 2001 at a cost of $49-million.
The cost of treating all 38 million people currently infected with HIV in the world would average out to $7-billion a year over 45 years, when the model indicates that cases would fall to less than one million.
"It would be a mistake for us to sit for another decade waiting for something miraculous to happen and come and solve the problem," Dr. Montaner said.
