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Vaccine to give fight against AIDS booster shot

In the first ever breakthrough in 26 years, an experimental vaccine reduced the risk of HIV, the virus that causes AIDS, in a third of the people vaccinated, reports Sanchita Sharma. Listen to podcastaudio | How AIDS vaccine may work | The breakthrough

health and fitness Updated: Sep 25, 2009 12:03 IST
Sanchita Sharma

In the first ever breakthrough in 26 years, an experimental vaccine reduced the risk of HIV, the virus that causes AIDS, in a third of the people vaccinated. The breakthrough

The biggest-ever Phase III trials done to test the safety and efficacy of an AIDS vaccine on humans showed lowered risk of HIV infection by 31.2 per cent among 16,000 healthy men and women in Thailand, trial-sponsors Global HIV Vaccine Enterprise announced on Thursday.

“For the first time in 26 years, we have a vaccine that confers protection in some people. It is not the vaccine that will go into production — that will take at least another three to five years — but the Thailand trial results offer hope that a vaccine against AIDS can work,” said Dr Alan Bernstein, executive director, Global HIV Vaccine Enterprise, speaking to HT from New York.

The vaccine may not work in Africa and India, where different subtypes of HIV-1 drive the infection. HIV-1 subtype B is predominant in the US and Europe, subtype E in Thailand and South East Asia, and subtype C in Africa and India.

“The Thailand vaccine was formulated specifically to protect against HIV-1 subtypes E and B, so it’s premature to say whether it will work in India, where subtype C is predominant. We need trials in India before we know,” said Sujatha Rao, director general, National AIDS Control Organisation.

In India, 23.1 lakh (2.31 million) people have HIV, but there is no data on new infections.

Worldwide, an estimated 6,800 people get infected with HIV every day, with young people under 25 years accounting for half of all new infections.

“Even though the immune response is moderate, the results offer hope because they follow big setbacks. In the past, most vaccines showed no effect and some even suggested an increased risk of HIV infection,” said Dr Charles Gilks, India Country Coordinator, Joint United Nations Programme on HIV/AIDS (UNAIDS).

“With this vaccine, we hope to understand the mechanism that offers protection and enhance it to offer 60-70 per cent protection,” said Dr Gilks. The vaccines against measles and tetanus, for example, offer over 90 per cent protection.

The Thai AIDS vaccine is a combination of Sanofi-Aventis’ ALVAC canary pox vaccine and AIDSVAX, made by VaxGen and now owned by the non-profit Global Solutions for Infectious Diseases.

Apart from Sanofi and Global Solutions, Global HIV Vaccine Enterprise stakeholders included the US Military

HIV Research Program, the US National Institute of Allergy and Infectious Diseases and Thailand Ministry of Public Health.

“All the people involved are meeting in New York next week to discuss and try to answer some of the questions, such as how does it confer protection, why isn’t the immune response 100 per cent, will it work against other subtypes. We hope we will have the answers soon,” said Dr Bernstein.

How they did it

The vaccine: A combination of Sanofi-Aventis' ALVAC canary pox vaccine and AIDSVAX, made by VaxGen and now owned by the non-profit Global Solutions for Infectious Diseases.

The volunteers: 16,000 healthy men and women at no additional risk of HIV infection.

The dose: Six vaccinations over six months -- four with ALVAC and two with AIDSVAX.

The duration: The volunteers were followed for six years.

How did the vaccines work? A two-vaccine combo was used in a "prime-boost" approach. The first vaccine primed the immune system to attack HIV and the second one strengthened the immune response to it.

What next? Need to boost immune response to at least 70 per cent for the vaccine to be effective

When will it be marketed? If the immune response is successfully heightened, the vaccine will take another 3-5 years to hit the market.

Can it be used in India? The Thailand vaccine protects against HIV-1 subtypes E and B, predominant in the US and Thailand, and not against subtype C predominant in India. Human trials in India will be needed to test its effectiveness.

People who made it happen: Global HIV Vaccine Enterprise stakeholders included the Thailand Ministry of Public Health, US Military HIV Research Program, the US National Institute of Allergy and Infectious Diseases, Sanofi Pasteur and Global Solutions for Infectious Diseases.