I am 22 years old and i have a boyfriend overseas, actually hes in early 50's. When he got here last July, i make love to him and he is the first man i made love to. My OB wanted me to have a vaccine against cervical cancer. How sure it is effective? Is it a lifetime? She want me for the reason that i have a boyfriend overseas. But i read from there that it is most effective if administered to young girls or young adults before they become sexually active, can it still be more effective even if i am sexually active?