HIV VACCINE TRIAL SUCCESS REPRESENTS A RAY OF HOPE

       Following last week's announcement by the Public Health Ministry and other agencies of a modest but historic breakthrough in HIV vaccine development, the question is now: What's the next step in the fight against the spread of HIV/Aids? In this interview with The Nation, director of the Thai Phase III HIV vaccine clinical trial, Dr Suppachai Rerks-Hgarm, discusses this and other related issues.
       Q: What is your feeling now the world's largest HIV vaccine trial, involving 16,402 volunteers, is complete?
       A: I am relieved as we have done a great job and come up with quality information to be analysed, despite world pessimism over development of an HIV vaccine. But I am still worried because my ultimate goal is to have a vaccine to prevent the spread of HIV/Aids, particularly in Thailand. We have not reached this goal, meaning an important mission still awaits us.
       Q: The researchers announced at the Public Health Ministry's Department of Disease Control press conference that the vaccine was 31.2 per cent effective in reducing the risk of HIV infection. Would you explain further.
       A: The result of this experiment meant people who received this vaccine had a 31.2 per cent lower risk of HIV infection than people who did not. We found only 51 out of 8,201 volunteers who received the prime boost combination of vaccine were infected with HIV, while 74 out of 8,201 volunteers who received the placebo vaccine were infected with the HIV virus. However, we compared the efficacy of the vaccine among volunteers who used a condom when they had sex and those who did not. The result showed there was no difference among both groups. We also found that most volunteers had reduced sexual risk behaviour, including reduced sexual partners, and were using more condoms after receiving the vaccine.
       Q: What was done to follow up on the volunteers and provide treatment for those infected with HIV?
       A: Volunteers could still access health services under their benefits provided by the government. Those 125 volunteers infected with HIV will receive free anti-retroviral drugs and treatment.
       Q: How do you explain the deaths of two volunteers during the trial?
       A: Two volunteers who died were infected with HIV but they received a placebo vaccine. One of them had been abroad and did not receive treatment there, fearing repatriation. This volunteer had decided to come back to Thailand to receive medication when the disease became severe. The other volunteer disappeared from the trial after receiving the vaccine. We could not track their records about symptoms and cause of death. But we can conclude that the vaccine was safe because it was produced from the synthetic HIV virus. There was no chance of getting HIV from injecting vaccine.
       Q: How will you develop this research for the next vaccine generation?
       A: We can do more studies in detail from the information and blood samples we collected from volunteers. This will help us understand [the vaccine] from different angles and provide important clues for development of the next generation vaccine. We also need opinions from local and international researchers. In the long term, we hope the next generation of vaccine will be more effective. Thanks to [what we learned from] the failure of the previous HIV vaccine trial, we have improved our methods. Now we have seen the world's first achievement in developing an HIV vaccine and we know exactly what we are going to do for the next generation of vaccine.
       Q: Will you release to the public the remaining information about the HIV vaccine trial?
       A: Of course. We need to inform people and listen to opinions from scientists and researchers to help us check and reconfirm information we did not get from the experiment. But the right to publish this study in academic journals is the research team's privilege. We made agreements with the HIV vaccine-makers - who own a licence to produce a vaccine - to reduce the price of their product if the vaccine is effective. But now we have to restart negotiations with them, as the trial's efficacy was not high enough for [its general] use. This does not mean we have no ray of hope. The success of this trial reflects that developing countries have the capacity to be partners with developed countries to discover a vaccine. So we are trying to change our position from buyer to co-developer. And for those countries not participating in the trial, the World Health Organisation and other non-profit organisations will help them negotiate with the vaccine-makers to reduce the price of the product. From now on, the project will invite the volunteers to hear their individual results and to know what kind of vaccine they received.
       Background to the vaccine trial
       The Thai Phase III HIV vaccine clinical trial, also known as RV144, tested the "prime-boost" combination of two vaccines: ALVAC HIV vaccine (the prime) produced by Sanofi-Pasteur, and AIDS VAX B/E vaccine (the boost) produced by Global Solutions for Infectious Diseases. This vaccine combination was based on an HIV strain common in Thailand. The RV144 was designed to test the vaccine strategy's ability to prevent HIV infection, as well as its ability to reduce the amount of HIV in the blood (viral load) of those who became infected after they enrolled in the study.
       The Ministry of Public Health conducted the study, together with Mahidol University and the US Armed Forces Research Institute of Medical Science, operating out of Thailand. It was sponsored with funds of Bt3.5 billion from the US Army Surgeon General.
       The Phase III vaccine study was launched in 2003 involving 500 Thai researchers and 16,402 non-infected volunteers - aged between 18 to 30 - with an average risk of HIV infection; half received the prime boost combination of vaccine and half received a placebo.
       The vaccinations ended in July 2006, and volunteers received an HIV test every six months for three years. They received counselling on how to prevent becoming infected with HIV at the beginning of the study, and every six months after the start of the trial, for a total of three and a half years.
       Before agreeing to participate, all volunteers were informed of and consented to the potential risks associated with receiving the experimental vaccine combination. Meanwhile, the International Data and Safety Monitoring Board did not identify any safety concerns after eight meetings following the trial's initiation.
       The study vaccines did not cause HIV infection because they are not made from and do not contain the entire virus, either live or killed.