It is thought to be the first study to definitively show a decrease in HPV in a community setting, whilst at the same time demonstrating the 'Herd Protection' that occurs when a critical mass of people are immunized against a contagious disease.
Jessica Kahn, MD, MPH, a physician in the division of Adolescent Medicine at Cincinnati Children's and lead author of the study, said:
"Infection with the types of HPV targeted by the vaccine decreased in vaccinated young women by 69 percent ...
Two of these HPV types, HPV-16 and HPV-18, cause about 70 percent of cervical cancer. Thus, the results are promising in that they suggest that vaccine introduction could substantially reduce rates of cervical cancer in this community in the future."
HPV vaccine has not been available for very long. The first registration was only in June 2006. The U.S. Advisory Committee on Immunization Practices recommends the vaccination of girls and women between the ages of 11 and 26 to reduce rates of HPV infection, because HPV infection can lead to cervical cancer and the vaccination was shown to reduce this.
Dr. Kahn and her colleagues at the Cincinnati Children's Hospital Medical Center gathered nearly 400 unvaccinated sexually active women between the ages of 13 and 16 who attended the care clinics in the city. The also took another 400 who had been vaccinated. This enabled them to compare pre and post vaccination infection rates.
It appeared there was a substantial decrease in infection rates with a 58% drop from 31.7% to 13.4%. The decrease was high amongst vaccinated patients with a 69% success rate of the vaccine, however, the unvaccinated girls also showed a reduction of 49%.
There is a danger, of course, that in hearing news like this many people would not bother with the vaccine of consider it important, and Dr. Kahn said she was impressed with the results, especially since many of the women were exposed to HPV before being vaccinated and only one dose was considered as vaccinated. She emphasized the need for vaccination of as many people in the population as possible to maintain the herd effect..
The study was a relatively short one with a small number of people and the subjects were mainly young black women on Medicaid insurance. It was also confined to a single city. Dr. Kahn stressed the need for more research to quantify the effectiveness of the HPV vaccine, but nonetheless her results are extremely positive.
Written by Rupert Shepherd