Can the following statements be reconciled:
- Condoms form an essentially impermeable barrier to HIV
- Sexual activities other than penetration carry a very low risk of transmission
- The consistent use of condoms reduces the risk of HIV transmission to about a fifth of what it would otherwise have been (source: Am Fam Physician. 2004 Oct 1;70(7):1268-1269 as summarized at aafp.org/afp/2004/1001/p1268.html)
Obviously the effectiveness of condoms is going to depend on them being used correctly, but surely they are not used so incorrectly that the effectiveness drops as much as these statements imply - assuming all 3 statements are correct, is there a more plausible explanation?