A FEW of the earliest 'worst-case' predictions about the extent of the Aids epidemic - going back to the early Eighties - did exaggerate the spread of the virus. However, since 1988, scientific advisers to the Government have consistently given accurate advice on the rise of Aids.
Newspapers that have fostered the belief that Aids has been exaggerated out of all proportion to the risk often quote predictions made at a time when widespread screening for HIV had not even started.
Andrew Neil, editor of the Sunday Times, said on The Frost Programme earlier this month that the Royal College of Nursing predicted in 1985 that there would be one million Aids victims by 1991 - which turned out to be a gross overestimate.
However, few Aids researchers accepted such estimates at the time. Britain, for instance, only introduced the blood test for HIV in the autumn of 1985 and there was next to no information about the prevalence of the virus in the population.
It was only in 1988, three years after HIV testing had begun, that a more accurate picture began to emerge of how the Aids problem would grow. In March of that year, the Government set up the Cox Committee to assess the possible course of the epidemic over the next two to five years.
The committee's conclusions were couched in uncertainties, which were often downplayed when newspapers came to reporting the figures. The first sentence of the conclusions stated that there was 'considerable uncertainty' due partly to the 'absence or limitations of relevant data'.
Despite such limitations, the scientists on the committee estimated that there were between 2,000 and 5,500 people in Britain infected with HIV through heterosexual contact. With hindsight, their lower figure was probably closer to the mark, but it can hardly be said that the scientists were wildly exaggerating the problem.
Another attempt to evaluate the extent of the future Aids epidemic came in 1990 with another government committee, this time chaired by Professor Nick Day, head of the Biostatistics Unit at Cambridge.
Again, estimates of the spread of HIV among heterosexuals were couched in caveats that often got lost in newspaper reports: 'There is great uncertainty in predictions of future cases due to transmission of HIV through heterosexual contact and injecting drug use,' the committee emphasised. 'This uncertainty would be much reduced if reliable estimates of HIV prevalence in different sections of the population were available.'
At the time the report was being prepared, anonymous screening of the heterosexual population had still not begun. This was crucial to determining the extent to which HIV had seeped out into the wider population. Without the data from such a screening programme, scientists were working very much in the dark and yet were still expected to come up with accurate predictions.
The first Day report nevertheless gave a planning projection for cases of Aids - set midway between an upper and lower estimate - that has since proved remarkably accurate. In no way can these Aids researchers be accused of exaggerating.
Anne Johnson, a member of the Day committee and lecturer at University College and Middlesex School of Medicine, has highlighted how difficult it is to predict the spread of HIV among heterosexuals: 'It is erroneous to arrive at conclusions in the early Nineties about the eventual prevalence of HIV, as it would have been to expect 15th-century epidemiologists in the decade after the introduction
of syphilis to predict its devastating effect throughout Europe in subsequent centuries.'