Two doses of the human papillomavirus (HPV) vaccine may be offering just as much protection against cervical cancer as the three-dose regimen which is now being used, as per a new U.S. government research.

The findings have come from an analysis of data from the National Cancer Institute's Costa Rica Vaccine Trial. A total of 7,466 women were enrolled for the study.The Journal of the National Cancer Institute has published the results.

The study was led by Aimee R. Kreimer of the division of cancer epidemiology and genetics at the U.S. National Cancer Institute.

The women were either given the HPV vaccine Cervarix or a Hepatitis A vaccine.

After four years, the researchers found that two doses of Cervarix offered the same level of protection against HPV infection as three.

Cervarix is one of two vaccines approved by the U.S.

The vaccine will prevent infection from certain strains of the human papilloma virus, which can cause cervical cancer. It is considered revolutionary because it's the first vaccine to prevent a type of cancer.

The HPV vaccine, approved in 2006, requires three shots over a six-month period. This is a regimen that is inconvenient and costly. But the present study shows that a two-dose vaccine may work as well.

However, it is still not clear whether a regimen of fewer than three doses will protect against HPV over a long period of time. For now, doctors will continue to recommend a three-dose regimen.

Worldwide, HPV is the most common sexually transmitted infection in adults.

Although most women infected with genital HPV will not have complications from the virus, worldwide there are an estimated 470,000 new cases of cervical cancer that result in 233,000 deaths per year.