The study that is done that American doctors rely so heavily on has in the data that it reduces the risk in diaper aged boys from a rate of 1 in 1000 to 1 in 3000. The African study showed that it reduces HIV transfer from around ~2.8% to ~1.6%, even though STI transfer is link more with behavior than equipment. You could kind of tell that the most infected country in the world happens to be the one with the highest percent of infant circumcision. Then with the Utah study that followed pubescent boys with circumcision linked injuries found that over 10% had 1. But you know Dr. Edgar s. (Forget how to spell his last name) Openly admitted to stacking the AAP board with his biased and still best he got was parents' choice.
So a 0.002% chance of preventing a UTI. A 1.5% chance of preventing an STI if he has straight sex with an infected partner. All with the cost of a 10% chance of messing his penis up in some way. Not to mention the potential psychological effects. Nah I'm good. No way I could ethically participate.