And for the first time, over 30 percent of those participating are women compared to less than 10 percent who did so in the first vaccine trials, which failed to produce the desired results.

This means that if things move as planned, Kenyans are likely to get vaccine results on time than was the case with the first one that dragged for along time.

“The turn out has been beyond our expectations. We had to tell the extra volunteers to wait because we could not go against the number that was approved by the government,” said Dr Omu Anzala, Kenya Aid Vaccine Initiative (KAVI) Project Manager.

Dr Crispin Kambili of International Aids Vaccine Initiative (IAVI), a US based organization, said the fast recruitment was an indication that the Kenyan scientists have mastered expertise of carrying out vaccine trials as their counterparts in developed countries.

“We are excited that the large numbers of volunteers will help us make informed decisions very fast on how to move the vaccine to the next stage.”

Dr Kambili, who is IAVI’s Africa Regional Medical Director, added that: “We are racing against time, and the smaller the number of volunteers the more difficult it is for us to make critical decisions on how to move forward very fast.”

According to Prof Job Bwayo, the vaccine’s Principal Investigator, the recruitment of the first vaccine was slow because they did not have highly trained personnel, many people were ignorant about what the vaccine was all about, and the government approval process was slow.

Currently, the government has put in place guidelines for such research. And for the first time, the Biosafety Committee constituted by the government a few years approved this vaccine.

“The approval process we went through was faster than the previous one that contributed to the delays we experienced in moving forward the trials conducted on the first vaccine,” says Prof Bwayo.

During the first vaccine, the scientists took longer to recruit the desired number of volunteers, resulting in the vaccine taking more time to finalize just one of phase.

Now they are saying they are likely to move to phase two of the study faster than what was the case in the past. IAVI is spending at least 71 million shillings (one million dollars) every year to run the activities of this vaccine at the KAVI site alone.

The first volunteer was vaccinated in January and each one of them is expected to be followed for a period of 12 months as the scientists determine the safety of the vaccine. The last volunteer, who was recruited this month, is to be monitored up to May 2006.

So far, the Kenyan scientists conducting the project say the volunteers who have received the vaccine have tolerated it well.

As they registered this progress, it also emerged that recruitment of volunteers in a study on the same vaccine started in Kericho, which is the first site to undertake such trials outside Nairobi

Walter Reed, the American Army Research arm, which works in collaboration with Kenya Medical Research Institute (Kemri), is behind the Kericho trials.

Dr Kambili revealed that although the trials on this vaccine are being conducted by several organizations, they have harmonized their research protocols so as to come up with comparable results.

“One of the things we trying to avoid is to get results on the same vaccine that cannot sufficiently tell someone the true picture of what is happening.”

These developments come as the world marks the World Vaccine Day today (18th May 2006). In Kenya, a Half Marathon race to commemorate the day is taking place today (18th May 2006) in Kericho.

If the phase one trials turn out to be successful, then the trials will move to what is called phase 2A, to determine the vaccine’s immunogenicity and dosage levels.

Unlike the first vaccine, four sites with high risk groups have already been identified where the vaccine is likely to be tested for the phase 2B trials that will be used to prove whether the vaccine works or not.

These include Kagemi and Kilifi, which are being handled by KAVI, Kericho handled by Water Reeds and Kisumu site under Centre for Disease Control of America.

Results from the Kagemi study indicate the prevalence rate in the area is 21 percent, standing out as one of the regions in the country with risk populations.

In Kifili, Mutwapa has been identified with high risk group, while CDC and Walter Reed are focusing in Kericho and Kisumu respectively for such sites.

Developed by the Vaccine Research Centre, an offshoot of America’s National Institute of Health IH, the vaccine is a combination of two vaccines: DNA and recombinant adenovirus serotype 5 (rAd5).

The DNA is designed to prime the immune system, with the rAd5 boosting it for better response. This combination produces potent specific immune cells that work against HIV.

Other studies have shown that a combination of DNA as priming agent and rAd5 for boosting regimens, have protected nonhuman primates against lethal challenge posed by the Ebola virus.

“Use of the rAd5 as a vector has been demonstrated to show good immunogenecity, and we hope this vaccine will also show good results,” said Dr Kambili.

Unlike the first vaccine that KAVI and Oxford University scientists abandoned after it failed to elicit the desired immune response on HIV subtype A, the current vaccine is designed to prevent someone from getting infected by any of the three sub-types, A, B, and C.

In Kenya and other countries in sub-Saharan Africa, over 65 percent of the HIV circulating is subtype A, while subtype C predominating Southern Africa and India, with B circulating mostly in America, Japan, Australia, the Caribbean and Europe.

Also, to make it potent, the vaccine is designed to attack the virus from a two levels. On one level, it is expected to elicit Neutralizing Antibodies that will disable the two key proteins – gp120 and gp41 - that enable the virus to infect a cell.

For those viruses that will not be destroyed by the antibodies and end up infecting the cell, then the second level, the Cellular Immune Response, will come into play.

In this case, when the infected cell takes a certain form, the immune cells, especially the Killer T-cells, will be alerted and respond by killing it before the virus replicates and infects more cells.

While most of the vaccines which have been tested so far are designed to induce a cellular immune response, it has remained a very tricky area for scientists.

A vaccine that elicits antibodies, although seen as the best way out, has too posed challenges to the scientific community.

Recent studies have however shown that a vaccine that is capable of induce neutralizing antibodies as well as cellular immune response is the best way out.

The vaccine was first tested by NIH in America in 2004, before moving the testing to other countries.

In recent times, research organizations in developed countries have been testing vaccine or other drugs they make on populations in their mother countries before subjecting other people, especially in Africa, on the same. This is to avoid accusation that they are using those in developing world as guinea pigs in their studies.

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