LOS ANGELES, Oct. 6 (Xinhuanet) -- A newly developed vaccine is 100 percent effective against cervical cancer in phase III clinical tests, pharmaceutical giant Merck Inc. reported on Thursday.

    The vaccine, labeled as Gardasil (quadrivalent human papillomavirus types 6, 11, 16, 18, recombinant vaccine), is designed to prevent human papillomaviruses HPV16 and HPV18 from infecting women and arousing cancer, according to the drugmaker.

    The two viruses are known to be responsible for 70 percent of cervical cancer cases.

    In a clinical trial covering more than 12,000 women from 13 countries, women aged 16 to 26 years were randomized to receive a three-dose regimen of either Gardasil or placebo at Day 1, Month 2,and Month 6. A group of 6,082 females received Gardasil and another group of 6,075 received placebo.

    The primary analysis of this trial, titled FUTURE II, evaluatedthe incidence of infections in women who received three doses of Gardasil, had no major protocol violations and remained free of HPV 16 and/or HPV 18 infection through month 7. That means the efficacy of the vaccine reaches 100 percent.

    A second analysis, including hundreds more women participating in the ongoing study, showed that after just one dose the vaccine was 97 percent effective.

    That analysis found only one of the 5,736 women who got the vaccine developed cervical cancer or precancerous lesions, compared with 36 among the 5,766 who got dummy shots.

    The analysis compared Gardasil to placebo in women who were notinfected with HPV 16 and 18 at enrollment and who remained free ofinfection through the completion of the vaccination regimen.

    "These are the first pivotal data to show that vaccination withGardasil reduced HPV 16 and 18-related cervical pre-cancer and non-invasive cervical cancer," said Laura Koutsky, principal investigator of this study at University of Washington.

    The data will be presented for the first time at the annual meeting of the Infectious Diseases Society of America.

    Cervical cancer is the second most common cancer in women and their No. 2 cause of cancer deaths, resulting in about 300,000 annual deaths around the world. At least half of sexually active men and women become infected with genital HPV. Enditem