Don't thow away the condoms just yet......

Talking of vaccines, the vaccine topic de jour yesterday, more so than even the progress of the swine flu vaccines through the various regulatory hurdles, was that of the new HIV vaccine. And how the media lapped it up!

"New Vaccine reduces the risk of contracting HIV by 31%!!" trumpet the media! "Up yours, all you naysayers," you who said a vaccine against HIV could never be produced!

Eye - catching coverage, I am sure you will agree, but was it justified? Lets look at some of the background.

1. This was a blend of 2 previous vaccines (ALVAC and AIDSVAX), neither of which had been shown to work on their own. The vaccine manufacturers themselves appeared surprised at the seeming success of this latest trial.
2. Even should the figure of 31% prove reproducible, it is worth bearing in mind that this still falls significantly short of the widely accepted minimum target efficacy for vaccines of 50% population protection.So the figures, if confirmed, signal cautious optimism, but would still require much work.
3. The articles and reports so prominently featuring the relative success of this vaccine trial have been released in advance of publication of the actual data - never a good sign, in my opinion. In some instances, the absolute figures have not even been offered!
4. 31% is a great, eye catching, memorable headline figure, but do the absolute figures justify the optimism? This is where it starts to get interesting - Total volunteers for the trial, 16,000 or so, test period between 2003 - 2006. 8,197 randomised to vaccine arm and 8,198 to placebo arm. Number of confirmed infected individuals in the placebo arm - 74; in the vaccine cohort - 51.

So this relative protection of 31% is based upon the difference between only 74 and 51 individuals - and only just qualifies as being statistically significant. Should one less individual have become seropostive in the placebo cohort, then the result would have been classed as statistically insignificant.

What I find interesting is the triumphalist tone adopted by some of the media. Again,as with swine flu coverage, I found the BBC article factual in tone with little opinion colouring it. Compare and contrast with, yet again to my disappointment,The Independent article , which doesn't even provide the absolute numbers!

Over the last few decades, there has been a massive investment in the development of an HIV vaccine, probably in the billions of dollars. Such a vaccine has been imbued with the hope of being the best method of HIV prevention. The failure of the various trials to date has lead to increasing pessimism amongst the majority of researchers that a successful vaccine could ever be manufactured. So the cynic in me asks this - Was all the hype surrounding the news of this trial more to do with justifying the cost of the existing trial and procuring future funding?

I am also curious as to why the health editor at The Independent is so upbeat about reports of as yet unpublished data from this latest HIV vaccine trial despite the small absolute numbers and the borderline statistical significance? Why didn't the article mention the absolute numbers at all? How do they justify such an optimistic tone over this one trial, with such small numbers and borderline statistical significance, and on the other hand have such an alarmist tone over the negligible risk posed by adjuvants present in the swine flu vaccines?

I am rapidly going off The Independent, especially when it comes to health stories.And another example of why it is important that you look at more than one news outlet.