Can HPV vaccinated individuals help prevent the transfer of HPV to unvaccinated
Posted Feb 11 2014 4:47pm
A new study sets out to determine if the vaccine is effective in reducing transmission
HPV infections are the most common sexually transmitted infections in the United States. In fact, more than half of sexually active people are infected with one or more HPV types at some point in their lives. Virtually all cervical cancers are caused by HPV infections, with just two HPV types, 16 and 18 are responsible for about 70 percent of all cases.
Prophylactic vaccines against certain high-risk HPV types have been shown to be effective in preventing infection. However, much remains to be understood on the effects of HPV vaccine on the blockage of transmission of target HPV types to sexual partners of vaccinated individuals. However, much remains to be understood on the effects of HPV vaccine on the blockage of transmission of target HPV types to sexual partners of vaccinated individuals.
Dr. Eduardo Franco, is James McGill Professor in the Departments of Oncology and Epidemiology & Biostatistics, Director, Division of Cancer Epidemiology, and Chair, Department of Oncology, at McGill University's Faculty of Medicine and lead author of a new study - called TRAP-HPV, an acronym for Transmission Reduction And Prevention with HPV vaccination.
This study at McGill University will examine whether vaccinating only one partner in a couple against the human papillomavirus (HPV) can help prevent transmission of HPV to the unvaccinated partner. This new study will examine whether vaccinating only one partner in a couple against the human papillomavirus (HPV) can help prevent transmission of HPV to the unvaccinated partner. This is a randomized placebo-controlled double-blind trial involving 500 sexually active couples.
Dr. Franco explains “this is the first study to look at whether unvaccinated partners of vaccinated individuals have a benefit in terms of protection from HPV infection.” "It will help us understand the important issue of herd immunity from HPV vaccination. If partner protection is sufficiently high we may be able to get adequate population level immunity from much less than 100% vaccination coverage and devote our scarce public health funds to other pressing needs."
According to Kristina Dahlstrom, postdoctoral fellow, Department of Oncology, Division of Cancer Epidemiology, “efficacy studies of the HPV vaccines generally look at genital HPV infections, but our study will also be looking at other anatomical sites that HPV infects, such as the anal and oral regions.” "Increasing the knowledge about HPV transmission dynamics will benefit cost-effectiveness studies and have implications for decision-making when implementing population-level vaccination strategies."
The study will vaccinate couples with Gardasil (Merck), the HPV vaccine, and the placebo will be vaccination with Havrix (GSK), a vaccine against hepatitis A. Those vaccinated with Havrix will still be susceptible to HPV infection. A couple can be randomized to both receive Gardasil, one receives Gardasil and the other Havrix, or both receive Havrix (the control group). Couples will be followed for one year with clinic visits to collect genital, anal, and oral samples to determine their HPV infection status. They will also provide information about their demographics and sexual behaviors.
Eligibility for the study is couples who;
Have not been vaccinated against HPV
Plan on remaining in Montreal for at least 1 year
Are in a new relationship that started no earlier than three months ago
Plan on having continued sexual contact with each other
Have no history of cervical, penile, oral, or anal cancers
Are not pregnant or plan on immediately becoming pregnant
Are willing to follow study procedures
If you and your partner meet the following criteria, you may be eligible for TRAP-HPV If you are interested in participating in this study you may contact Ms. Allita Rodrigues at mailto:email@example.com for more information.
Each year, about 32,000 new cases of cancer are found in parts of the body where human papillomavirus (HPV) is often found. Most people will not even know they have it since HPV usually has no signs or symptoms.
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In 2010, a McGill study called HITCH (HPV Infection and Transmission in Couples through Heterosexual activity), also from Dr. Franco's team, found more than half (56 per cent) of young adults in a new sexual relationship were infected with HPV. Of those, nearly half (44 per cent) were infected with an HPV type that causes cancer. HPV is transmitted through sexual contact and persistent infections by specific types of HPV can cause cancer.
A study published online July 9, 2012 in the eFirst pages of Pediatrics, from The Cincinnati Children's Hospital Medical Center is believed to be the first to show a substantial decrease in HPV infection in a community setting as well as herd protection – a decrease in infection rates among unimmunized individuals that occurs when a critical mass of people in a community is immunized against a contagious disease.
This study aimed to compare prevalence rates of human papillomavirus (HPV) in young women before and after HPV vaccine introduction to determine the following: (1) whether vaccine-type HPV infection decreased, (2) whether there was evidence of herd protection, and (3) whether there was evidence for type-replacement (increased prevalence of nonvaccine-type HPV).
The results of the study show that the HPV vaccine has been effective at reducing the number of infections that people are getting, while also protecting those people who haven’t been vaccinated.
In 2006 and 2007 , Dr. Jessica Kahn, MD, MPH, physician in the division of Adolescent Medicine at Cincinnati Children's and lead author of the study and colleagues recruited 368 young women between the ages of 13 and 16 from two primary care clinics in the city of Cincinnati. The young women had sexual contact but none were vaccinated. In 2009 and 2010, they recruited a different group of 409 young women in the same age range, more than half of whom had received at least one dose of the vaccine. The researchers compared pre- and post-vaccination HPV prevalence rates.
The prevalence of vaccine-type HPV decreased 58 percent overall, from 31.7 percent to 13.4 percent. The decrease was high among vaccinated participants (69 percent), but also was substantial for those who were unvaccinated (49 percent).
In their conclusion the researchers write “Four years after licensing of the quadrivalent HPV vaccine, there was a substantial decrease in vaccine-type HPV prevalence and evidence of herd protection in this community. The increase in nonvaccine-type HPV in vaccinated participants should be interpreted with caution but warrants further study.”
More information on HPV can be found online at the CDC website.
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