There is strong evidence of the early benefits of the human papillomavirus (HPV) vaccine on reductions in cervical dysplasia and possible reductions in anogenital warts (AGW) among girls aged 14 to 17, according to a new study released today.
The HPV vaccine, which protects against four types of HPV shown to cause cervical cancer and AGW, is offered free through school-based programs to young girls across Canada. Despite this protection, use of the vaccine has been lower than needed in a number of regions.
“We observed a large and significant reduction in cervical dysplasia, a precursor to cervical cancer, in girls as young as 14 to 17 years of age,” said Leah Smith and Linda Lévesque, Institute for Clinical Evaluative Sciences (ICES) researchers at Queen’s University. The study, carried out in collaboration with researchers at McGill University also found the vaccine is starting to decrease the occurrence of AGW in this population.
HPV is a sexually-transmitted infection that affects most people at some point during their lives. Although the vast majority of these infections self-resolve without further complication, others can lead to important health consequences such as AGW and cancers of the cervix, anus and penis.
HPV vaccine programs are generally aimed at immunizing young girls before the onset of sexual activity when the possibility of previous HPV infection is low.
“The fact that these benefits were observed in such a young age group strengthens current recommendations that vaccination should not be delayed,” said Smith, lead author on the study published in the journal Pediatrics.
This study followed 260,493 girls, half of whom were eligible for Ontario’s publicly funded Grade 8 HPV vaccination program in its first two years (2007/08 and 2008/09). Researchers found that among the 2,436 cases of cervical dysplasia documented between Grades 10-12, 44 per cent fewer cases occurred in eligible girls who received the vaccine. This means that one case of cervical dysplasia was prevented for every 175 eligible girls vaccinated.
"The vast majority of cases of cervical dysplasia prevented by the HPV vaccine would not have progressed to cervical cancer. Nevertheless, these early reductions are of great importance given the burden of cervical dysplasia on the emotional and physical well-being of young girls, as well as on the healthcare system,” said Lévesque, senior author of the study.
This study was funded by the CIHR.
“The early benefits of human papillomavirus vaccination on cervical dysplasia and anogenital warts,” was published today in Pediatrics.
Authors: Leah M Smith, Erin C Strumpf, Jay S Kaufman, Aisha Lofters, Michael Schwandt, Linda E Lévesque.
ICES is an independent, non-profit organization that uses population-based health information to produce knowledge on a broad range of healthcare issues. Our unbiased evidence provides measures of health system performance, a clearer understanding of the shifting healthcare needs of Ontarians, and a stimulus for discussion of practical solutions to optimize scarce resources. ICES knowledge is highly regarded in Canada and abroad, and is widely used by government, hospitals, planners, and practitioners to make decisions about care delivery and to develop policy.
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