The long-awaited full results of the Thailand RV144 vaccine trial, presented at AIDS Vaccine 2009 in Paris this morning, yielded nothing unexpected.
The data and report, published in The New England Medical Journal today, confirmed what is already known: the vaccine had a modestly protective effect (31% efficacy compared to the placebo), was safe and well tolerated.
The trial investigators stood by their announcement last month that the effect was statistically significant – which has been a topic of much controversy in the last few weeks. One of their main points was that the statistics should be measured against the design of the trial and they explained why.
Colonel Nelson Michael, director of the US Military HIV Research Program, who presented along with Supachai Rerks-Ngarm, from the Thai Ministry of Health, Thailand, said: “This is the first evidence that a prime-boost HIV vaccine regimen may prevent infection and represents a significant step forward for vaccine research.
“While it will not likely have any immediate public health benefit, we are hopeful that the findings will guide additional studies and accelerate research efforts toward a more effective vaccine.”
Scientists at the plenary commented that the cellular immune results, released today, were what they had anticipated, and that important antibody tests had not yet been done so they could not comment on the vaccine’s ability to boost the humoral immunity (antibody immunity).
In summary, researchers still have no immunological clues as to why this vaccine was partially successful and this is one of the major questions that they will investigate now.
On the other hand, much of the data Dr Glenda Gray, director of the Wits Perinatal HIV Research Unit, presented from the interim analysis of the Phamibili study in South Africa (which was suspended in September in 2007 for showing no effect) was made public for the first time.
The excitement that abounds among many of the 1100 delegates at AIDS Vaccine 2009 in Paris this year is tangible. In just 12 months, since the last annual conference in Cape Town which was excellent, the field has experienced many encouraging developments.
The most well known of these are the preliminary results of the Thailand vaccine trial released last month. The statistical significance of these results is controversial but whatever the majority concensus, this is the first human clinical trial to show some protection against HIV.
All eyes will be on the release of the full data of this Thai Phase IIb trial for the first time tomorrow and presentations dealing with the immunogenicity and questions that these raise, among others.
From all accounts the immunogenicity results are not significant yet the vaccine had a modest success, suggesting that another marker is needed to know which HIV vaccines will be safe and effective. The follow up analysis to the Phambili trial in South Africa will also be presented.
Meanwhile Swedish researchers are reporting a small vaccine study in Tanzania has shown even better results than the Thailand trial, and their findings could be another positive development.
Another fascinating topic is the research on the elite controllers – a very rare group (about 0.5%) of the population who manage to keep their HIV viral load under control and CD4 counts high despite being infected. A handful of them have been identified in South Africa so far in KwaZulu-Natal.
A number of scientists attending this conference are studying their genes and searching for clues on how they do this, in order to inform improved vaccine designs in future.
A more controversial topic is whether it is time to take more risks in the type of vaccines being made, for example, to use viral-replicating vectors instead of sticking in the safer zone of non-replicating vectors.
The delivery of vaccines also seems to be important with in vivo electroporation giving better results than normal delivery. This could be an effective way to deliver a DNA vaccine against HIV.
That’s not all but my head is reeling and it’s time to do a report on the opening session of the conference that has just ended for The Times online.
Dr Alan Bernstein, the executive director of the Global HIV Vaccine Enterprise (one of the conference hosts with the National Agency for Research on AIDS and Viral Hepatitis in France) told the opening session: “This week we will hear very exciting and very important new data that holds great promise for the field and for the world.”
But he warned, as did other HIV leaders, that lack of funding threatens to derail the current momentum.
I will send reports to The Times as well as posting updates throughout the next three days until the conference closes on Thursday.