I now see that Auvert, who led the Orange Farm randomised control test (but not of course double-blind, nor was the control group given a placebo operation or the strong warnings against unprotected sex that the circumcised experimental group was given), is on the team that made these calculations.
They seem to have made a number of unspoken assumptions:
- circumcision is risk-free and cost-free (and any costs will not be deducted from other prevention measures)
- all circumcisions are equally effective
- circumcision will have no effect on the frequency of intercourse, or the likelihood of using a condom
I have a strong suspicion, from the way many of these studies are written up, that the agenda of some people is not (or not so much) to prevent HIV, but to promote circumcision: one sees the same people involved, where circumcision is the only common factor.