Gus Cairns Responds to the CDC's "Lowered Expectations"
I personally think the CDC is realistic about this, and prevention advocates unrealistic. It would be very difficult to reduce the number of new cases over the next five years by 50% for several reasons. Reducing HIV incidence in an established epidemic is quite a tough nut to crack. For instance, see the forecasts that serosorting was behind an apparent 50% reduction in incidence in San Francisco gay men a couple of years ago. On further investigation it was found that the reduction in incidence wasn’t anything like as big as at first seemed, because behaviour changes compensated. Incidence in urban gay male populations in the US and Europe has been remarkably steady since 1999, varying between 2.5% and 4% a year but usually sticking around 3%.
Part of the problem is that if 50% of new infections come from people in acute infection themselves, they’re the people least likely to know they’re infected and least likely to change behaviour accordingly.
Partly it’s because the epidemic has its own momentum – the more people you have with HIV, the more people there are to infect others (at least until you reach ‘saturation point’ in a particular population and there are fewer at-risk people left to infect that ones already infected – this may be starting to happen in the African-American population).
And partly it’s because I don’t think the ‘HAART effect’ on increased lifespans for PLWHAs has yet fully worked its way through the epidemic curve: if people with HIV start living 30 years with the virus instead of 3, they have to be 10 times safer in order to infect less than one other person (the magic figure that makes the epidemic shrink, not grow).
Even in places like Uganda, reductions in prevalence (we find) have been more about people dying en masse of AIDS and much less about an actual decline in infections.
I’m also uncomfortable with calls for unrealistic targets to be retained because “even if [they’re] just rhetorical, to fight for more programs and more funding.”
Well, the history of HIV is peppered with examples of people crying doom and disaster that never happens - and forecasting bright dawns that never show (do I have to utter the words ‘HIV vaccine’?) If you keep doing this, it becomes ‘crying wolf’ and the criers become discredited. If the scientific evidence suggests 10% is achievable and 50% isn’t, then go with the 10% I say. [There are exceptions to this rule – such as, some would argue, the ‘3 by 5’ campaign – but even in that case not achieving 3 million on treatment by 2005 was seen by many as a failure by the WHO, even though achieving half that could be seen as a success].
It must never be about fighting “for more programs and more funding” but for effective programs and effective funding.
The real reason we should be fighting for prevention programmes is not because they’ll make things a lot better, but because if you don’t have them, things will get a lot worse, and often in unexpected ways and in unexpected populations. Examples of that one abound!
Prevention is now a marathon, not a sprint. Behaviour change in an established epidemic (as opposed to a sudden emergency, as in the 1980s) can take generations to achieve. It took 50 years to halve the proportion of the population who smoke. It may take as long to reduce – in any lasting way – new HIV cases. We’re in this – barring some magic-bullet prevention technology – for the long haul.
---Gus www.guscairns.com
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