The vaccine blocks the human papilloma virus
A vaccine for cervical cancer has been found to offer protection for at least four-and-a-half years in trials.
The vaccine protects against strains of the human papilloma virus (HPV) which are thought to be the most common cause of cervical cancer.
HPV is spread through sex, so it is planned to offer the vaccine to girls before they become sexually active.
The US study, by Dartmouth Medical School in New Hampshire, is published online by The Lancet.
Cervical cancer kills more than 1,000 women in the UK every year.
It is thought that two strains of HPV, 16 and 18, are responsible for more than 70% of cases of the disease.
The vaccine, under development by GlaxoSmithKline, is designed to protect against these two HPV strains.
The US researchers took smear test samples from 800 women who took part in a trial of the vaccine. Each woman either received three doses of the vaccine or a dummy pill.
Analysis showed the women given the vaccine had high levels of antibodies against HPV-16 and HPV-18 for up to four-and-a-half years after receiving the last dose.
The vaccine was effective against persistent and new infections and also protected against infection with HPV-45 and HPV-31 - the third and fourth most common types of HPV.
Lead researcher Dr Diane Harper said the results showed the vaccine was safe, and effective in the long term.
She said: "These findings set the stage for the wide scale adoption of HPV vaccination for prevention of cervical cancer."
Dr Anne Szarewski, clinical consultant for Cancer Research UK, said: "Since the vaccine is being targeted initially at girls of around 12, it is very important that the protection lasts as long as possible.
"The vaccine is totally effective against cervical abnormalities due to HPV types 16 and 18, which is very encouraging.
"The fact that it also protects against two more HPV types is extremely exciting, as this may mean that around 80% of cervical cancers could be prevented with this vaccine.
"This is very good news for women in the UK."
A new survey from GlaxoSmithKline has found that just one in 25 British women was aware that HPV leads to cervical cancer.
Although a quarter of the 978 women (26%) questioned had heard of the virus, only 4% knew it was the main cause of cervical cancer.
Almost a third (31%) of women said they did not know the cause of the cancer, while 36% said it was related to "sexual practices".
Glaxo submitted its vaccine to the European Medicines Agency for approval in March.
A second similar vaccine is being developed by Merck and Co, who applied for marketing approval in Europe and the US in December.