A vaccine that protects women against a virus that causes cervical cancer is effective for more than four years, researchers said on Thursday.

They found that women given GlaxoSmithKline Plc’s cervical cancer vaccine Cervarix had high levels of antibodies against two of types of the human papillomavirus (HPV) for up to 4.5 years after receiving their last dose.

“These findings set the stage for widescale adoption of HPV vaccination for prevention of cervical cancer,” said Dr Diane Harper, of Dartmouth Medical School in New Hampshire, who conducted the trial.

Cervical is one of the most common cancers in women. Each year 470,000 women around the world are diagnosed with the disease and 230,000, mostly in the developing world, die, according to the International Agency for Research on Cancer (IARC) in Lyon, France.

HPV is a sexually transmitted infection. Strains 16 and 18 of the virus are responsible for more than 70 percent of cervical cancers.

Results of a European survey released on Wednesday of more than 1,500 women in five EU countries showed that only 5 percent could identify HPV as the cause of cervical cancer.

Harper and her team followed up 800 women who took part in the original trial of the vaccine in which it was compared to a placebo. Their research is published online by The Lancet medical journal.

Women given the vaccine not only had high levels of antibodies against HPV-16 and HPV-18 but the levels did not decrease over time.

The vaccine also protected against new and persistent infections and was effective against HPV-45 and HPV-31, the third and fourth most prevalent cancer-causing types of the virus.

“The results show sustained immune response and long-term efficacy against HPV-16 and HPV-18 infection,” Harper added.

Glaxo submitted the vaccine to the European Medicines Agency for approval in March. But Merck & Co. Inc’s Gardasil vaccine was filed for marketing approval in Europe and the United States last December.

Merck is marketing the vaccine in partnership with Sanofi-Aventis in Europe.