Dr. Stan Block, who practices in a six-pediatrician group in Bardstown, Ky., with a large adolescent population, explains that “the lifetime risk of getting cervical, anal, vaginal, or vulvar precancer or cancer goes from about 1 in 20 without vaccination to 1 in 50 with vaccination,” and that the risk of venereal warts similarly drops from 1 in 10 without vaccination with Gardasil to about 1 in 100 with vaccination.
“We explain that even precancerous lesions can have serious consequences, like surgery and the inability to have children,” said Dr. Block, who estimates that his practice has an 85%–90% HPV vaccination rate in female patients.
Dr. Michael E. Pichichero, director of the Rochester (N.Y.) General Hospital Research Institute, advises telling patients and parents that “studies show without a doubt that when you vaccinate at a younger age, you get much higher immunity levels.”
And Dr. Charles Wibbelsman, a pediatrician who is chief of adolescent medicine at Kaiser Permanente in San Francisco, advises telling patients that at least “10,000 women die each year of cervical cancer and countless others have cervical cancer, and that HPV causes cervical cancer.”
▸ Safety. At least several studies have shown that the vaccine would receive greater acceptance if it was perceived to be safe by parents.
“I tell parents that the vaccine has now been received by literally hundreds of thousands in this country, and that there are no serious adverse events associated with the vaccine,” said Dr. Freed. “Then I say that in the same time period, there likely have been at least several thousand young women who have been infected with HPV who will develop precancerous cervical lesions and may go on to develop cervical cancer.”
Others said they refer parents who are concerned about safety to the CDC's Web site for vaccine safety profiles (www.cdc.gov/vaccinesafety/vaccines/hpv
According to the CDC Web site, approximately 32 million doses of Gardasil were distributed in the United States from the time the vaccine was licensed in 2006 until September 2010. All serious adverse event reports made to the Vaccine Adverse Event Reporting System have been fully investigated, with staff finding “no pattern or clustering … to suggest they were caused by the HPV vaccination,” the Web site says.
Syncope and fainting are common in preteens and teens after injections, the CDC notes, making the recommended 15-minute postvaccination observation period extremely important. Patients should lie down or sit for this period of time.
▸ Duration of Efficacy. Manufacturers have tracked vaccine recipients for up to 8–10 years at this point, with no “breakthrough cases” of HPV infection, sources said.
“We can [say] that, as with any new vaccine, we [don't know] how long efficacy will last, but that we do know the vaccine is highly immunogenic, that we're seeing no breakthrough cases in the recipients being followed, and that we know protection will last at least 7 and a half years, and likely significantly longer,” said Dr. Bocchini. If needed in the future, a booster dose will become available.
▸ Vaccine Differences. The most important facts for parents and/or older patients to know, several physicians said, is that both Gardasil and Cervarix protect against the two strains of HPV (types 16 and 18) that are believed to cause 70% of all cervical cancers, and that Gardasil also protects against HPV-6 and −11, the most common cause of genital warts.
Teens should know the value of protecting against genital warts, they said. “There are about a million new cases of genital warts each year in this country, and the amount of money spent treating them is equivalent to the amount of money spent treating cervical cancer,” not to mention the fact that genital warts cause significant anguish, said Dr. Gall.
Dr. Pichichero, however, said that Cervarix contains a novel adjuvant that is believed to be responsible for its ability to generate a greater antibody response to HPV−16 and −18, compared with Gardasil. Higher antibody titers may translate into a longer duration of protection, he said.
Cervarix also has been shown, he said, to afford some level of cross-protection against other HPV strains that are responsible for a small yet significant proportion of cervical cancer cases. Although such differences should be weighed in the long term, right now it seems that parents are more concerned about safety and experience with the vaccines, and physicians should focus on this, he said.
Dr. Block has done research for both manufacturers and is on the speakers bureau for Gardasil (Merck's HPV vaccine). Dr. Pichichero has served as a consultant for both Merck and GlaxoSmithKline, the manufacturers of Gardasil and Cervarix, respectively. Dr. Gall said he was working on clinical trials and is a speaker for GSK and Merck. The other physicians reported no disclosures.
