If you have a child who is at least 9 years old, you may be weighing whether he or she should get vaccinated against human papillomavirus (HPV).
HPV is a common sexually transmitted infection that can cause genital warts and cervical cancer. Men and women can carry it. HPV sometimes plays a role in other cancers as well, including cancers of the vulva, vagina, penis, anus, and throat.
There are two HPV vaccines: Gardasil and Cervarix. Gardasil, which protects against four HPV types (6, 11, 16, and 18), is approved by the FDA for use by females aged 9-26 to help prevent cancer of the cervix, vagina, and vulva; genital warts, and anal cancer. It's also approved for males aged 9-26 to help prevent genital warts and anal cancer.
Cervarix targets HPV types 16 and 18. It's approved for females aged 10-25 to help prevent cervical cancer.
Both are relatively new vaccines -- the FDA approved Gardasil in 2006 and Cervarix in 2009. And that makes some parents uneasy. Should they be, or are their fears unfounded?
Resistance to the HPV Vaccine
Most pediatricians recommend routine vaccination against HPV for girls, and to a lesser extent, for boys (the CDC made a "permissive" recommendation regarding boys and the HPV vaccine. It can be given to them between 9 and 26 years old, but it need not be routine, partly because of the vaccine's high cost). However, the rate of full immunization among girls aged 13-17 in the U.S. in 2009 was about 27%. The same year, about 44% of the adolescent girls received at least one of the three shots in the series.
"Of course we would like coverage to be higher. However, it is not that different from rates for other new vaccines soon after licensure," says Lauri Markowitz, MD, a medical epidemiologist with the CDC. She led the team that reviewed safety trials for the CDC and recommended Gardasil in 2007.
Getting vaccinated against HPV is recommended before becoming sexually active. Markowitz says studies show that many parents wait until their daughters are older before getting the shot, which is recommended for girls 11 or 12.
Another reason for the low coverage, Markowitz says, is that getting vaccinated against HPV takes two additional appointments, ideally within 6 months, and adolescents typically don't make that many visits to their doctor or other health care provider.
Lingering Safety Concerns
Minnesota mom Lesley Doehr plans to have her 11-year-old daughter, Sally, vaccinated against HPV. Her pediatrician recommended it, and after reading up on it and talking to other parents, she believes the benefits far outweigh the risks.
"If there's any chance of reducing cancer, why wouldn't you try it? That is my bottom line," says Doehr, an assistant regional treasurer for Cargill, Inc. She says she'll probably wait until Sally is 13, "when boys are in the vocabulary.''
And, she adds, "It won't hurt matters that there will be a couple more years of research."
But Linda May, who lives in suburban Indiana, wonders if changes her daughter Laura has experienced since getting her first Gardasil shot in February 2010 are from the vaccine.
May says Laura, a former athlete and star pupil, is fatigued and always achy. Her menstrual cycle is irregular.
Laura doesn't complain, Linda says, but the family can see she is not herself. The Mays have spent countless hours talking to doctors. No diagnosis has been made, but a few have theorized that the vaccine triggered an autoimmune response, she says.
The family plans to file a claim with the Department of Health and Human Services' National Vaccine Injury Compensation Program, which has recorded 88 injury and 8 death claims related to the HPV vaccines and two legal settlements.
May is not against the HPV vaccine. But she wants to see it taken off the market until more safety reviews are done. "I know many girls who've had (the vaccine) and are fine," May says. "It needs to be looked at."
Gardasil is made by the drug company Merck. Richard Haupt, MD, who heads Merck's adult clinical vaccine research group, says clinical trials and post-licensure trials of Gardasil showed no increase in the rate of autoimmune conditions in vaccine recipients -- and Merck has looked for them.
In one surveillance study, Merck pre-specified 16 autoimmune conditions to look for in 200,000 women patients who had received one dose of Gardasil. "We saw no signal of an increase rate of autoimmune conditions," Haupt says.
Gardasil, he says, has been shown to be safe in repeated trials."The benefits of vaccination clearly outweigh any risks," Haupt says.
HPV Vaccine's Safety Record
Despite a solid safety record for Gardasil and Cervarix, many adverse events have been registered with the Vaccine Adverse Events Reporting System (VAERS).
As of late November 2010, more than 18,000 complaints had been reported. That's twice the number of reports following injection with Menactra, another vaccine for adolescents that protects against meningitis. VAERS, co-sponsored by the CDC and the FDA, collects data on any adverse event that follows a vaccine -- whether or not it's caused by the vaccine. The information helps the agencies analyze and track the most common complaints.
Most VAERS reports on the HPV vaccine are for minor events, such as fainting and/or having pain at the site of the shot. But there are also reports of deep vein thrombosis (blood clotting) and Guillain-Barre Syndrome, a rare neurological disorder.
The CDC is aware, of course, of the reports of illness, and acknowledges that concerns about the vaccine's safety may be keeping people from getting immunized.
However, says Claudia Vellozzi, MD, deputy director of the CDC's Immunization Safety Office, the HPV vaccine has been shown to be as safe as meningitis and Tdap vaccines.
VAERS, Vellozi points out, is a passive reporting system, so there is no way to know if the vaccines caused the adverse events. Also, she says, VAERS is subject to underreporting and simultaneous reporting.
That is, there's no way to know if the vaccines caused the adverse events, or whether the numbers are on point.
"In our review of available vaccine safety data, FDA and CDC have concluded that the benefits of HPV vaccination continue to outweigh its risks and the vaccine is recommended," Vellozzi says.
As of September 2010, about 32 million doses of Gardasil had been distributed in the U.S.
In October, after reviewing reports from managed care organizations that tracked millions of patients who'd received Gardasil -- about 600,000 doses -- the CDC again concluded that Gardasil poses no serious health problems. The analysis looked at side effects within 42 days of the shot.
The Institute of Medicine (IOM) is also reviewing adverse events of several vaccines introduced since 1997, including HPV vaccines. Its findings are due in June.
Finding Middle Ground
Time will tell how safe any vaccine is, says Karen Smith-McCune, MD, a professor of medicine at the University of California-San Francisco. Smith-McCune, a gynecologist, was an early and vocal skeptic of the HPV vaccine.
"This is a new product. It is possible there are risks that have not come to light yet because of the newness of the product, and that's what VAERS is for: to assure us we haven't missed something unknown. We don't know about safety until something's been around a long time," she says. "It's valid for parents to ask why they should do it."
Smith-McCune says she resisted the adoption of the HPV vaccine early on because cervical cancer is quite rare and preventable in females who get regular pap smears. And most of the time, the body fights off HPV without harm. She says she feels the vaccine was "shoved down our throats, as parents."
Today, Smith-McCune says research has convinced her that the HPV vaccines reduces precancerous conditions and abnormal pap smears -- not earth-shaking, but significant. Women who get the vaccine will have fewer visits to the doctor, she says.
"A lot of people get [Pap smears] and have abnormalities that need to be evaluated and treated," says Smith-McCune. "To give a vaccine for a cancer that is not likely may be good, but reducing irregular Paps is a benefit."