From an abstract:
The combination of long-term concurrent sexual partnerships and high infectiousness early in HIV infection has been suggested as a key driver of the extensive spread of HIV in general populations in sub-Saharan Africa, but this has never been scientifically investigated.
Really? Call me skeptical, but okay, let's take him at his word.
We use a mathematical model to simulate HIV spreading on sexual networks with different amounts of concurrency.
A mathematical model, as opposed to an actual survey? Hmm...
The models show that if HIV infectiousness is constant over the duration of infection, the amount of concurrency has much less influence on HIV spread compared to when infectiousness varies over three stages of infection with high infectiousness in the first months.
So people sleeping around helps get the ball rolling on an AIDS epidemic, but less so as husbands pass it on to their wives and mothers to their babies. That makes sense.
The proportion of transmissions during primary infection is sensitive to the amount of concurrency
The more people sleep around in the early wave of the infections, the greater the proportion of transmissions. Makes sense.
He seems to be saying there's a certain degree of influence, especially in the first wave of transmissions, but concurrent partnerships have less influence in subsequent waves.
But it's done with a mathematical model. All well and good, but I find it less credible than actually surveying transmissions.
All these studies amuse me because they typically confirm what so-cons know: if you don't sleep around, don't do drugs, reserve sex for marriage and stay faithful, you will never get an STI. It's so blindingly obvious, but public health officials don't seem to want to state it because it's not political correctness. They want to work with people's weaknesses, which is what gets them in trouble in the first place, instead of helping them to be strong and resist all these temptations.