Test Drive

We may be moving on the vaccine development front but now the question is how close are we to it. No one knows the answer, the trials may take years and even then nobody can be hundred per cent sure about its efficacy in humans.

Says Pradeep Seth, Head of the Department of Microbiology and incharge of the vaccine research at AIIMS: 8216;8216;The magnitude of the scientific challenges includes the hyper variability of the virus, animal models are of limited guidance and relevance to humans can be known after clinical trials with human volunteers only.8217;8217;

Both these groups seemed to have identified the 8216;candidate8217; vaccine and are now ready for Phase-I trials. According to officials in IAVI, the trials for their vaccine are likely to start sometime next year and are likely to take two years.

The vaccine has been tailored to Indian needs and includes genetic components derived from HIV-1 group, Subtype C strain, that is found in India. 8216;8216;About 95 per cent or more infections in India are of Subtype C strain so the vaccine has to be tailormade for India. For if we have to control our own disease we have to prepare our own vaccine ,8217;8217; says Seth.

The trials on humans have to be conducted in three phases. Phase-I trials are conducted with a small group of healthy volunteers who are at a low risk for HIV infection, to test the vaccine for safety and initial information on how the body8217;s immune system will respond to the vaccine to fight against HIV infection. 8216;8216;Phase-I does not access the efficacy of the vaccine. It tests the vaccines for immediate reactions in humans. We would be using 39 volunteers for Phase-I trials, 30 would be given the vaccine and 9 would be given plasibo, which may even be simple water,8217;8217; says Anjali Nayar, Director of IAVI.

Phase II trials usually involve several hundred healthy and low risk volunteers and are conducted to obtain additional safety and immunogenicity data. It also gives information about different populations and vaccine dosage.

Phase III trails are large scale field trials to assess the efficacy of the candidate vaccine for preventing infections or disease. They usually involve several thousand volunteers, who are at a relatively high risk of getting HIV infection. They include sex workers, IV users and other such groups who have high chance of contracting the disease. Phase III trials are long and complex and in the most optimistic scenario it takes 7 to 10 years between phase I and phase III. So even if things go as planned, it will take the vaccine about 12 years to hit the stores.

The obvious questions in all this are, can the vaccines be given to healthy volunteers, what is the selection criterion and how ethical are the trials? The volunteers according to the researchers would be enrolled after telling them about all the pros and cons in the testing. 8216;8216;Abroad they advertise for volunteers through media but in India we are not likely to do that,8217;8217; says Anjali Nayar, Country Director of IAVI.

Why do we need a vaccine? According to Nayar, no comprehensive prevention programme can be complete without a vaccine. 8216;8216;We8217;re not saying we should forget the traditional means of controlling the disease but vaccine research can8217;t be neglected.8217;8217;

A vaccine is a substance that teaches the body8217;s immune system to recognise and protect against a disease caused by an infection agent, HIV virus in this case. The vaccine triggers an immune response system in the body, so when the body is exposed to the infectious agent, it is ready to fight.

The vaccine in this case is called the 8216;Modified Vaccinia Ankara8217; or MVA which according to scientists uses different methods from those used for other diseases. This according to them is to prevent infection in the healthy. 8216;8216;There are a number of approaches for making vaccines. Two of the most common approaches use killed or weakened cells. The good news is that no HIV vaccine can cause HIV infection to trial volunteers. The vaccines are made of pieces of HIV: genes and proteins. This ensures that the vaccines cannot cause AIDS,8217;8217; says Seth.

Nayar says they are using all the six genes of HIV. Seth too appears to be following a similar pattern. The initial tests for both vaccines will be conducted at Pune8217;s National AIDS Research Institute NARI. But whether the two groups will come together is still a question.