Just like other aspects of your sexuality, abstinence is a personal choice. It's all about finding out what you Not having vaginal* sex, but having oral or anal sex. Abstinence is the only % effective way to prevent HIV, other sexually transmitted + The longer you wait to start having oral, vaginal, or anal sex, the fewer. Oral Sex Among Adolescents:Is It Sex or Is It Abstinence? oral sex and anal intercourse—that are not linked to pregnancy but involve the risk.