Sunday Times - Sunday, November 16, 2003
Claire Keeton

The country's first trial started last week and now South Africa joins the US, Britain, France and Switzerland in simultaneously testing more than one experimental Aids vaccine.

The urgency to step up the search for a vaccine was highlighted when US biotechnology company VaxGen, whose AIDSVAX product is the only one yet to be tested in large-scale efficacy trials, revealed this week that its vaccine had failed to protect volunteers in Thailand against HIV.

This was expected, following VaxGen's February results from an earlier trial involving about 5,000 volunteers in the US and Europe - which found the vaccine to be ineffective.

VaxGen president Don Francis urged the international public health community "to redouble the effort to develop an effective vaccine". Dr Seth Berkley, president of the New York-based International Aids Vaccine Initiative, said the Thailand outcome showed the need to speed up vaccine development. "Given the stage of the Aids epidemic, it is a disgrace that AIDSVAX is the only vaccine that has been taken to efficacy trials," he said by telephone.

"We need simultaneous trials of multiple vaccines in many countries so that we can move as fast as possible."

Science has moved on since the Thai trial was launched four years ago and South Africa is testing cutting-edge vaccine technology in its trials.

Said Berkley: "Other Aids vaccine candidates, employing more promising design strategies that are different from AIDSVAX's, are in trials."

AIDSVAX did not prevent HIV infection among the 2,546 Thai injecting drug users who tested it, nor did it slow down the progression of HIV among volunteers who became infected - although it had no negative side-effects.

During the trial, 106 of the volunteers who received the vaccine became HIV positive, while 105 volunteers who received a placebo were infected.

AIDSVAX, made with small protein parts of the virus, cannot cause HIV infection on its own. While 3.1% of the drug-injecting volunteers got HIV through their behaviour, despite receiving regular education and counselling, volunteers reported marked reductions in risk behaviour.

Another positive result was the commitment by 90% of the volunteers to completing the study.

Berkley said: "Although AIDSVAX was found not to work, the trials themselves were a success. VaxGen demonstrated that it is possible to conduct large-scale trials in both industrialised and developing countries."

The International Aids Vaccine Initiative says that more than 10,000 volunteers have taken part in vaccine trials, past and present.

Worldwide there are about a dozen vaccine candidates being tested in trials .

Dr Tim Tucker, director of the South African Aids Vaccine Initiative which is co-ordinating the trials, said: "What is happening in South Africa is a model for the world. We have local scientists working in collaboration with multiple international partners."

The Medicines Control Council has approved three experimental Aids vaccines for trials and two are in the first phase (of three) to test safety and immune responses.

The trials are being conducted in Soweto at the Peri-Natal HIV Research Unit at Chris Hani Baragwanath Hospital, and at the Medical Research Council's HIV Vaccine Research Unit in Durban.

Baragwanath trial investigator Dr Efthyia Vardas said the process went smoothly this week. Her team hoped to finish vaccinating 14 Soweto volunteers from both trials by the end of next week.

The first three volunteers were vaccinated in Durban this week.

Vardas said: "We are disappointed by the [VaxGen] results, but it does not directly affect us."

She said her team would do rigorous screening to see which vaccines showed the most potential to take into the large-scale, efficacy phase of trials, which was still years away.

South Africa's vaccine trials:

The AlphaVax replicon vector vaccine, based on HIV subtype C, which is most common in Southern Africa. This trial started last week in Soweto and this week in Durban.

The MVA (modified vaccinia Ankara) vaccine, based on subtype A HIV, found mostly in East Africa.

This trial started this week in Soweto.

The Merck vaccine, based on subtype B HIV, found mostly in the West. This trial is expected to start in January.

The only completed trials:

VaxGen's AIDSVAX B/E, based on subtypes B and E. This was tested on 2,546 volunteers in Thailand and the result - that it failed - was released this week.

VaxGen's AIDSVAX B/B, based on subtype B. This was tested on some 5,417 volunteers in Europe and the US, and the result - that it was ineffective - was released in February.

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