How could an adult putting his saliva in direct contact with an infant’s open wounds possibly not be dangerous???
If a doctor spit on the instruments he was using to examine (not to mention inserting like shots, tongue depressors etc.)your child with would you be O.K. with that??
Certainly it carries certain dangers. The question is how large those dangers are, and how important the reasons to do it are. And then how those interests balance.
The question of how large the danger is, should be ascertained by the doctors.
The question of how important the reasons to do it are, should be ascertained by the rabbis.
The balancing of the interests, should be done by the rabbis, since that itself is the question of how important the reasons to do it are.
In any event, I’m betting, that the bris itself is far more dangerous than the added risk of metzitza b’peh. And Health will back me up on that, or shoot me down on that.