The cost of bringing HIV/AIDS under control has an official price tag: US $10 billion a year from 2005. But where did that figure, the benchmark for financing treatment and prevention, come from?
Stefano Bertozzi, an economist who was part of the team that produced the estimate, explained that the target amount was based on "crystal ball kind of estimations" which made a lot of assumptions.
But they were still useful in mobilising funds for organisations such as the Global Fund to Fight AIDS, Tuberculosis and Malaria, as well as indicating how much each country could access.
When working on the model, resource needs were viewed within the
constraints of existing country infrastructures, as it was unrealistic to base estimates on improved financial and health-care systems, Bertozzi said.
"The money is not an estimate of the resources needed to care for all people living with HIV/AIDS, nor does it amount to how much is needed to prevent all new HIV infections by 2005."
"It is not an estimate of how much should be in the Global Fund because the Fund is only one part of the international resources needed," he told PlusNews.
The model had applied an idealised view of antiretroviral drug pricing. "In our model, the poor pay less than the rich."
This would be of no help, however, in predicting how much could be saved with lower antiretroviral drug prices.
The pattern of drug prices was "far from homogenous" and could not be predicted. "We found that the negotiation capacity of the country played a bigger role than need in securing better deals."
Brazil, for example, has a per capita income higher than Ecuador, but paid three times less for AIDS drugs.