HEALTH-SOUTH AFRICA: New HIV Vaccine Trials Raise Hopes
| Saturday, 10.25.2008, 09:19 AM |   (1576 views)

CAPE TOWN, Oct 20 (IPS) - After two HIV vaccine trials were halted for safety reasons last year, a new trial is set to commence within the next few months in South Africa and the United States. Scientists will test a new vaccine formula produced in South Africa. It will be the first time a HIV vaccine manufactured in a developing country will be trialed in the developed world.

Last year, trials using Merck Adenovirus 5 (AD 5) in South Africa as well as in the US and Australia had to be suspended because the US trial showed increased susceptibility to HIV acquisition among uncircumcised men.

Dr John Moore of the Department of Immunology and Virology at Weill Cornell Medical College in New York, said the "vaccines were simply not good enough to stimulate the necessary immune responses at a sufficient level" at the Global HIV Vaccine Enterprise's AIDS Vaccine 2008 Conference in Cape Town last week.

Not all health experts are convinced about the benefits of further vaccine trials, however, doubting that scientists will ever be able to develop an effective vaccine against HIV because of the unique nature of the virus.

"HIV is an amazingly diverse virus. There can be 10,000 plus variations of the virus and it is constantly changing. Because the virus mutates rapidly it is difficult to develop a vaccine," explained Alan Bernstein, executive director of the Global HIV Vaccine Enterprise, an international alliance of scientists, researchers and donor organisations.

Risk control

Experts are also concerened about the health and safety of trial participants. "More basic research should be done prior to us testing the next candidate vaccine," cautioned Francois Venter, president of the Southern African HIV Clinicians Society, while generally supporting efforts to find a vaccine.

"We desperately need a vaccine, even if it takes a generation. We need to keep looking for every possible option."

At the conference, researchers said vaccine trials will from now on focus on finding out how to help the body produce antibodies to prevent infection with HIV altogether. Dr. Lynn Morris, head of the AIDS unit at South Africa’s National Institute for Communicable Diseases, said this was a necessary step as scientists did still not know enough about how the human immune system deals with HIV.

Scientists complaint that lack of financial support from governments impacts negatively on research outcomes, especially in countries like South Africa, where HIV/AIDS policies and their delayed implementation have been criticised by experts all over the world. However, the research community now pinned its hopes on newly appointed health minister Barbara Hogan, who replaced disputed Manto Tshabalala-Msimang just a few weeks ago.

Hogan told conference delegates that she was deeply committed to making HIV/Aids a priority during her tenancy: "There cannot be any more important meeting at this time. This is the continent, the region and a country in most need of evidence-based intervention to the HIV and Aids epidemic."

Hogan said she believed that it was not too late for South Africa to improve its health care provision. "The fact that 500,000 people are already receiving ARVs (antiretroviral treatment) in this country is proof that the damage (done by the previous health minister) is being repaired."

She admitted, however, that she felt challenged when being appointed as minister of health.

Ethical concerns

Vaccine researchers said they were highly cautious about not repeating the same mistakes from previous trials and vowed to closely adhere to ethical boundaries in the race to be the first to find a vaccine.

"It would be unethical to embark on future trials if the same risk factors as those in the (previous) trials were present," said Professor Ruth Macklin of the Albert Einstein College of Medicine in New York. "The best course of action would be to avoid future trials that include probable causes of enhanced susceptibility (of HIV infection)."

"The question is, for example, if there should be exclusion criteria for uncircumcised men," Macklin said, since the health of uncircumcised men was put at risk during previous trials.

Scientists need to weigh up potential benefits and risks for trial participants carefully before embarking on a new series of tests.

"We need to consider benefit to individuals and benefit to science and society. In most research trials there is no guaranteed benefit. The drug or vaccine being tested is experimental -- it may or may not work," said Professor Keymanthri Moodley of the Bioethics Unit at the University of Stellenbosch.

"In the case of Aids vaccine trials, the risks are significant, but the benefits, if an effective vaccine is developed will be enormous," she added.

To lower risks, the upcoming vaccine trials will initially take place on a small scale before they are tested widely. The new products, SAAVI MVA and SAAVI DNA, will be tested on a small group of 48 participants -- 36 people from Johannesburg and Cape Town and twelve from Boston, said Dr Glenda Gray, researcher with the HIV Vaccine Trials Network (HVTN) and the South African Aids Vaccine Initiative (SAAVI).

"The participants will be men and women from low risk groups, including some who are celibate and some who are in monogamous relationships with known HIV-negative partners," she further explained.

SAAVI DNA has been developed by researchers at the University of Cape Town’s Institute for Infectious Diseases and Molecular Medicine, while the MVA vaccine has been conceptualised by UCT scientists and beenn developed and manufactured with the input of international biotech company Therion and the US-based National Institute of Health.

 

Source: IPS



Stephanie Nieuwoudt

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