In what sounds like yet another made-up-by-the-media trend, all of one teen is claiming to be involved in biting and blood exchanges to demonstrate romantic passion and intimate friendship. While the doc quoted has legit concerns about infections, let me tell you why this is preposterous:

• This is the exact kind of shit that freaks teens out, which is why vampires work so well as a metaphor for sex.
• Vamps and their human lovers don't bite each other in Twilight. Humans aren't physically able to break through vampire skin. Vamp bites mean death or vampirism. Which brings us back to human-on-human action, and that is strictly prohibited in Twilight.
• The Vampire Diaries and True Blood do feature blood exchanges, but it's really only kinky sex stuff in True Blood. And while teens no doubt watch True Blood, they, too, would be freaked out by the INSANE sex scenes. Which means that they wouldn't want to do that kind of stuff because it is too freaky.

Ergo, the entire thing is too freaky, even for freaky teens. One high school does not a trend make.