One of the ways to help prevent cervical cancer and/or HPV infection is by taking a vaccination with HPV vaccine. I read it somewhere and it says that ideally females should get the vaccine before they are sexually active. This is because the vaccine is most effective in women/girls who have not yet acquired any of the HPV types covered by the vaccine. I'm just wondering, what if the female had sex only once and no protection was used and the guy did not ejaculate into the vagina. In other words, the female is sexually active. Well, if she had sex even once, its still considered as sexually active right? So what if the female is sexually active, like how I described it? Is there any difference? I mean, the female can still take the vaccination but is there any side effects or its the same as a female who is not sexually active since they guy did not ejaculate? thank you (: