A study recently showed that HPV vaccine helped protect women against several types of cervical cancer for up to 7 years. Seven years. Pretty good.
2650 young women were vaccinated with quadrivalent HPV vaccine and there were no cases of severe cervical dysplasia or of cervical cancer in the next 7 years.
The HPV vaccine is a series of 3 vaccines which can be given between ages 9 to 26 regardless if the patient has already begun sexual encounters or if she has a history of HPV (as the vaccine can help protect her from other high-risk HPV types).
Hope this helps.