July 18th, 2011
12:52 PM ET
The evidence is mounting. Another study has found that PrEP - pre-exposure prophylaxis - is relatively safe and can prevent HIV transmission in couples where one partner is already infected with the virus.
The data from the study, called the HPTN 052 trial, released Monday in the New England Journal of Medicine at the International AIDS Society Conference in Rome. Researchers enrolled nearly 1,800 couples in Botswana, Kenya, Malawi, South Africa, Zimbabwe, Brazil, India, Thailand and the United States.
Fifty-four percent of the couples were from Africa; half of the infected partners were men. Those infected, with CD4 counts between 350 and 550, were randomly broken into two groups. In one group, the infected partner received antiretroviral drugs when they were enrolled. In the other, therapy was delayed until after their CD4 count fell below 250, or they suffered an AIDS related illness.
CD4, or T-Cells are a type of white blood cell that helps the body fight infections like viruses and bacteria. The higher your count, the stronger your immune system which helps reduce complications of HIV. When the CD4 count falls below 200 a person has AIDS.
Researchers found for those who got antiretroviral therapy (ART) early, the rate of transmission dropped by 96% compared with those who were treated later. HIV transmission occurred in just 39 people. Twenty-eight of those were directly linked to the HIV-infected partner. Of that 28, only one was from the group that got early treatment. HIV patients that got early therapy also had less HIV-related illness.
"HPTN 052 demonstrated that early initiation of ART by the infected partner in heterosexual couples, where one partner is HIV-infected and the other not, is highly effective in decreasing transmission of HIV to the uninfected partner," said Dr. Anthony Fauci, director, National Institute of Allergy and Infectious Diseases at the National Institutes of Health. "With these recent advances, we now have an unprecedented opportunity, based on solid scientific data, to control and ultimately end the AIDS pandemic. Of course, global implementation of HIV interventions, including the scale-up of the delivery of ART, must be accelerated, and this will be costly. A truly global commitment is essential. In this regard, major investments in implementation now will save even greater expenditures in the future; and in the meantime, countless lives will be saved."
The drugs used included Combivir, a combination of zidovudine and lamivudine; lopinavir and ritonavir or Kaletra–also known as Aluvia; and the combination tenofovir and emitricitabine whose brand name is Truvada. Last week, two different African studies, one of uninfected heterosexual men and women in Botswana, and the other of heterosexual couples in Kenya and Uganda, found Truvada significantly reduced the risk of transmission in study participants.
In the HPTN study, 82% of the transmissions occurred in Africa. Researchers say more frequent sexual activity and less condom use could be a reason for increased transmission there. Study investigators also saw higher viral loads in HIV patients in sub-Saharan Africa versus patients from developed countries.
Adverse events most often reported included infections, gastrointestinal problems, nervous system disorders and psychiatric issues. Some patients were found to have pulmonary tuberculosis; the majority of those cases were seen in India. More adverse events were seen in patients that got the drugs early. Study authors say the reason is unclear and more follow-up is necessary.
Researchers admit the study, funded by NIAID, is not without limitations. They say the couples were "stable" and possibly not representative of the general population. They were also counseled and given condoms, which authors say could have contributed to the low rate of infection.
New data from the iPrEx study is also being released this week at international AIDS meeting. In iPrEx, a trial that spanned four continents, daily PrEP with Truvada reduced HIV infections in men who have sex with men, or MSM. It was one of the largest studies ever conducted and the first in Asia or Africa that focused on MSM. Eleven new analyses will be presented.
"These new analyses confirm the safety and efficacy of PrEP in MSM and strengthen our belief that PrEP is an important HIV prevention tool with the potential to prevent significant number s of new HIV infections," said iPrEx Protocol Chair Dr. Robert Grant, Gladstone Institutes and the University of California at San Francisco. "When we viewed along with the Partners PrEP and TD2 data in heterosexual men and women, these findings make a compelling case that providing broad access to PrEP could reduce the human and financial cost of the epidemic significantly."
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