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HPV vaccine on the horizon — Will it be added to immunization schedules?
When you review immunization schedules with your adolescent patients this year, will a vaccine for human papillomavirus (HPV) be added to your discussion list? While no vaccine has yet been approved, recent scientific advances signal that such a vaccine soon may become a reality.
HPVs are the major cause of cervical cancer. HPV-16 causes approximately 50%-60% of cervical cancers, and HPV-18 causes another 10-20%.1 The American Cancer Society (ACS) estimates about 10,370 cases of invasive cervical cancer will be diagnosed in the United States in 2005, and about 3,710 women will die from the disease.2
Just-presented results from a Phase III trial show that an experimental vaccine developed by Merck & Co. in Whitehouse Station, NJ, was completely successful in protecting women against precancerous or noninvasive cervical cancer caused by human papillomavirus (HPV) types 16 and 18.3
The Gardasil quadrivalent recombinant vaccine protected all the women who received an initial dose of vaccine followed by a dose at two months and at six months. This cohort, which underwent 17 months of observation, included 5,301 women ages 16-23 who were recruited at 90 research sites in 13 countries.
A total of 5,258 women were inoculated with a placebo vaccine and underwent the same inoculation schedule. Twenty-one were found to have high-grade precancerous cervical lesions or noninvasive cancer.3
The presentation follows similar published data from the vaccine’s Phase II study, which indicate the quadrivalent HPV vaccine reduced the incidence of HPV infection and any HPV-related diseases by 90% compared with placebo.4
GSK Biologicals in Rixensart, Belgium, also has a vaccine, Cervarix, in advanced clinical trials. Research presented in mid-2005 on the bivalent vaccine, which targets strains 16 and 18, indicates it also provides cross-protection against strains 31, 45 and 52.5
Merck says it plans to file for FDA approval by the end of 2005, with GSK to soon follow.6
How to administer?
Getting a vaccine to market is one step in the prevention wheel. If such a vaccine is approved, how and when will it be administered? Many public health officials would like to see the HPV vaccine become part of the standard roster of shots that children, especially girls, receive just before puberty.7
This question was addressed during a recent meeting of the Advisory Committee on Immunization Practices (ACIP), which aids the federal government in designing the most effective means to prevent vaccine-preventable diseases. The panel’s guidelines are widely accepted in setting vaccination schedules.
At the meeting, members reviewed results from a survey of American Academy of Pediatricians members, designed to gauge pediatricians’ knowledge about HPV disease and their willingness to recommend an HPV vaccine. Pediatricians are willing to administer a vaccine for HPV and are much more likely to vaccinate older female patients (16-18 years vs. 10-12 years), says Nicole Liddon, PhD, a medical sociologist in the division of STD prevention at the Centers for Disease Control and Prevention, who presented the material.
The No. 1 barrier to administering a potential vaccine would be the concern that reimbursement would not be adequate, Liddon states. About half of the pediatricians who responded to the survey perceive parental refusal of the vaccine as a potential barrier to vaccination.
"The study also showed that there are gaps in pediatrician knowledge about HPV disease, and that more education on HPV and the HPV vaccine may be needed," states Liddon.
Will shot be accepted?
Human papillomaviruses are a group of more than 100 viruses. More than 30 HPVs are primarily sexually transmitted.1 Some conservative groups are against making the HPV vaccine mandatory and cite fears that it could send a subtle message condoning sexual activity before marriage.7
Since public health officials are looking at administering the shots in young adolescents, how will immunization be received by their parents? Research undertaken by scientists at Indiana University in Indianapolis indicates that parents will be in favor of such a move, says Gregory Zimet, PhD, professor of pediatrics and clinical psychology and lead author of the research.8
"I think most parents are really interested in protecting their children," he says. "The primary or overriding moral value is protecting their children from disease and from harm."
Will providers want it?
What will be providers’ stance on the HPV shot? Based on his research, Zimet contends that they will be interested in such a vaccine. In a survey of members of the American College of Obstetricians and Gynecologists, Zimet found that professional society recommendation is important for acceptability of a potential HPV vaccine.9
"If ACIP recommends it and the FDA licenses it, I think the professional organizations will fall into line," Zimet says.
Before any vaccine is introduced, providers will have to be educated on how to talk with patients on the benefits of the vaccine, as well as given specific terminology to ease concerns of patients and parents.10
Getting HPV on the radar screens of providers is an important preparatory step, says Zimet. "Cervical cancer is not something that affects children, but prevention is something that has to go into effect during childhood," he notes.