Gardasil, a vaccine created by drugmaker Merck & Co which aims to protect against a sexually transmitted virus linked to cervical cancer, triggered a stronger immune response in young adolescents than in young women in a late-stage trial.
The sexually transmitted human papillomavirus (HPV), is a cause of cervical cancer, which is the second-biggest killer of women worldwide.
Merck says in the trial, which involved 1,529 people, it was found that adolescent males and females aged 10 to 15 receiving the vaccine, produced a significantly higher level of anti-viral antibodies, compared with young women aged 16 to 23.
Three groups of patients were tested with the three-dose regime: males aged 10 to 15 years, females aged 10 to 15 years old, and females aged 16 to 23 years old, and responses to the vaccine were measured by the level of anti-HPV antibodies in the blood.
Adverse events reported included higher rates of fever within 15 days among the younger patients.
Merck said the data from the Phase 3 trial supports earlier studies in young women that found the vaccine cut down the incidence of infections, including cervical pre-cancers and genital warts.
The company says the "bridging study", the first trial to look at young people ages 10 to 15 years old, aims to assess the effectiveness of the treatment in the older group compared to the younger population based on immune responses.
Eliav Barr, head of clinical research for HPV vaccines at Merck, says that this is the first time they have had adolescent results,and it means is that both children as well as adults, respond to the vaccine.
Merck, is in a race with rival GlaxoSmithKline, who are also working on their own vaccine called Cervarix, and analysts are forecasting a fierce marketing battle between the drugmakers.