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Realistic interpretation of recent claims by researchers about the prevention of HIV/AIDS requires 'informed scepticism' about the public statements of scientists.

When scientific results get distorted in the press, it is often journalists — or their headline writers — who get the blame. Indeed, scientists often base their reluctance to speak to journalists on fear that their work, and particularly the uncertainties that surround it, may be misunderstood. But this concern can mask an equally damaging tendency for which scientists are themselves partly to blame, namely a desire to exaggerate the significance of their research specifically to pursue a particular agenda through attracting press attention.

In many cases, the results can easily be shrugged of, and are at most irritating. But in other instances the attention can be damaging, as it may lead to shifts in social behaviour that are not justifiable on the basis of the facts alone. In some cases, of course, as in the reluctance of British consumers in the early 1990s to eat home-grown beef out of fears of contamination with Mad Cow Disease, this shift may be sensible; hence public enthusiasm for what is known as the "precautionary principle". In others, however, it may be dangerous.

Two recent events have highlighted this issue, both connected with the prevention of AIDS. One has been the widespread publicity given to the claim that unhygienic medical practices, rather than unsafe sex, have been the principle cause of the rapid spread of HIV/AIDS in Africa (see HIV transmission claims stir controversy). The second has been claims made for the first AIDS vaccine to go through clinical trials that, although it failed to protect its main intended recipients — namely white Americans — it appears to have had a significant effect in providing such protection to black and Asian trial participants (see Mixed results from AIDS vaccine trial).

Both claims are currently hotly contested in the scientific community. And both certainly raise important hypotheses that — because of their potential impact on the course of the AIDS epidemic — deserve not only close scrutiny by experts, but also informed public debate. The challenge, however, for scientists and communicators alike, is how to ensure that the debate is a productive one, and how to avoid legitimate efforts to promote novel perspectives on significant issues from undermining more conventional policies that are already proving to be effective, if only in a limited way.

The threat of 'dirty needles'

Take, for example, what has become known as the 'dirty needles' story. This was prompted by the publication last month of three papers by an international group of researchers who claimed to have shown that close analysis of epidemiological data in Africa during the late 1980s suggests that the role of unhygienic medical practices in the transmission of HIV had been grossly underestimated. Indeed, while the World Health Organisation (WHO) claims that this only accounts for about 5 per cent of known HIV cases, the authors of the papers argue that the actual figure is closer to 60 per cent.

If true, the claim could have enormous implications for the priorities of both international aid agencies and national governments in the region. For this reason alone, it deserves to be taken seriously, and if necessary to require a close re-analysis by others of the data presented, and of the statistical techniques used to analyse it (the WHO is holding a meeting in Geneva later this week to do precisely that).

What is disturbing, however, is the satisfaction, verging on glee, that those promoting this apparently heretical position appear to be taking in their actions, with apparently little regard to the potential wider impact. It may be fun to take a poke at the AIDS establishment with papers that carry titles such as 'Mounting anomalies in the epidemiology of HIV in Africa: cry the beloved country', or even 'Let it be sexual: how health case transmission of AIDS in Africa was ignored'.

But there is an issue of both professional and moral responsibility involved. Is it really justified to treat the whole subject in such an apparently frivolous way when, as both the WHO and patient-support groups on the ground have been quick to point out, reports presenting such conclusions as proven fact could undermine not only campaigns to encourage safe sex, but also confidence in broader immunisation programmes?

AIDS vaccine — a partial success

The case of the AIDS vaccine trials is more complex, but in many ways similar. Here the controversial claims do not relate to the main results of the trials; both the company that developed the proposed vaccine, VaxGen, and those who have long been critical of its strategy in promoting a vaccine that only targets antibodies, agree that the vaccine has failed in its main goal. But there is serious disagreement over the interpretation of data that appears — at least theoretically — to point to an unexpected result, namely that the vaccine had been effective for blacks, Asians and mixed-race people involved in the trial.

The possibility of an unexpected breakthrough is certainly there. In the trials, the vaccine appeared to be about 78 per cent effective in blacks and 68 per cent in Asians; if confirmed by further studies, the results could indeed prove to be of major significance. But, given the relatively small number of individuals from each group involved in the study, is this sufficient to justify a US newspaper headline that is featured on the official UNAIDS website (even with a disclaimer): "Vaccine for AIDS shows promise"?

Company officials say that it is. VaxGen chief executive officer Donald Francis — intriguingly one of the first individuals to recognise the AIDS epidemic as it spread in San Francisco's gay community in the early 1980s — has been quoted as stating that "the trend is there; you can't ignore it". Others, presumably keen to rescue something positive from an otherwise gloomy set of conclusions, are reported to be playing down the scientific uncertainties in presenting the results to the company's investors.

Yet here again the jury remain out. Critics of VaxGen's analysis point out that important questions remain to be answered about the degree of certainty that can be attached to them, and suggest that the chances of the results arising by chance have been underplayed. In a colourful metaphor, one such critic has said that grouping the results of blacks and Asians together is equivalent to "a subgroup analysis based on signs of the zodiac".

The case for informed scepticism

There are no quick or easy solutions to the social dilemmas raised by these two highly-publicised reports. It would be entirely wrong, for example, to argue that the results, and the issues that they raise, should not have been raised in the media until there was a greater scientific consensus about them. That is a form of censorship that will only protect vested interests.

Nor, conversely, can the finger be easily pointed at the journalists and editors who present these stories. There are important points reflected here about the extent to which a rush into print — a tendency that has been enhanced by Internet journalism — can be the enemy of a more reflective type of journalism that seeks to place research results in a context. But most competent journalists are keen to do the latter, particularly on a subject as sensitive as AIDS. (Intriguingly, for example, the BBC appears to have withdrawn the initial version of its online news item on the epidemiology studies, headlined "Dirty Needles 'Spread African AIDS'", and replaced it with a new version of the same story under the headline "Dirty needles research rejected"; the first version can no longer be found on its website).

The resolution can only lie in increasing the sophistication with which public messages about research are analysed and interpreted. Contrary to those who claim that there is a need to rebuild trust in the scientific community, these two events point in a very different direction — the need to develop an informed scepticism (or, to turn it around the other way, a 'critical appreciation') about the statements of scientists. The 'informed' bit is what requires greater public understanding of science. The 'scepticism' not only allows us to see scientists as subject to the same human temptations as the rest of us, but also permits hype — even from mouths of researchers — to be recognised for what it is.

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