UCSF experts on human papillomavirus (HPV) and cervical cancer screening voiced concerns and some cautious optimism about the effectiveness, cost and long-term safety of a newly approved HPV vaccine at a September 12 Department of Obstetrics, Gynecology and Reproductive Sciences grand rounds presentation. The session was entitled "The HPV Vaccine: What We Know Versus What We Hope."
HPV is the most common sexually transmitted infection. About three-quarters or more of the US population has, or will become infected with, some type of HPV. However, in many cases, the virus is eliminated from the body over time. The risk of infection increases with the number of sex partners one has. HPV is responsible for nearly all cases of cervical cancer.
The vaccine, Merck's Gardasil, received Food and Drug Administration marketing approval in June. It prevents new infection with two HPV strains that currently account for 70 percent of cervical cancers.
Gardasil also targets two additional HPV strains that cause about 90 percent of cases of genital warts. Phase III clinical trial results for a second vaccine to prevent cervical cancer, developed by GlaxoSmithKline, have not yet been announced.
The US Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices recently recommended that Gardasil be administered routinely to 11- and 12-year-old girls. Physicians also would have the option of giving the vaccine to girls as young as 9 under their guidelines.
HPV Vaccine: Who Should Get It? Who Will Pay?
Cervical cancer disproportionately affects the poor. It is a leading cost of cancer death among women in developing countries. In the United States, due to widespread screening through Pap smears, cervical cancer is not a leading killer- about 3,700 women die from the disease each year. Still, the disease disproportionately affects the US poor, as well, and they can least afford to pay for vaccinations.
And unlike most vaccines, Gardasil is expensive - $360 for the three doses, noted George Sawaya, MD, associate professor of obstetrics, gynecology and reproductive sciences and director of the Cervical Dysplasia Clinic at San Francisco General Hospital Medical Center. That is more than twice the price of the next most expensive vaccine, for hepatitis B, he said.
Panel speaker Michael Policar, MD, MPH, is medical director of the California Family PACT (Planning, Access, Care and Treatment) program, which provides family planning services to eligible, low-income men and women. The federal government, which funds 90 percent of the program, has already indicated that it will not fund human papillomavirus (HPV) vaccination through PACT, according to Policar.
The state government also may choose to include the vaccine in its Vaccines for Children Program. Girls covered by Medi-Cal - the state's version of the federal Medicaid program - would then be eligible to receive the vaccine. A separate decision would determine whether adult Medi-Cal patients also would be covered.
Karen Smith-McCune, MD, PhD, associate professor of obstetrics, gynecology and reproductive sciences and director of UCSF's Dysplasia Clinic, said she would be more enthused about an HPV vaccine that targeted more cancer-causing types of the virus than just the two targeted by Gardasil. Screening is effective, she said, although a vaccine that better prevented HPV infections and cervical cancer could justify less frequent screening exams, thereby saving money.
"In this country, there is no emergency," she said. "We do a great job with screening."
Some panelists also noted that it may be too early to foresee possible long-term risks associated with vaccination. There is no threat of infection due to the vaccine, which contains no live virus and no viral genes. However, the aluminum adjuvant used to elicit stronger immune responses appeared to be responsible for a high frequency of short-term irritation. A disproportionate number of cases of rheumatoid arthritis also were observed in the vaccinated group - but given the relatively small study size and duration, the number was too few to be statistically significant.
Sawaya expects better evidence of vaccine benefits to emerge, but does not think the evidence is strong yet. It may be premature to make a "$2 billion per year investment for a hope," he said, referring to the estimated cost of vaccinating low-income women and girls, as recommended by the Centers for Disease Control and Prevention committee, that is to be covered through federal programs.
Preventing Cervical Cancer in Developing Nations
Anna-Barbara Moscicki, MD, professor of pediatrics and director of UCSF's Teen Colposcopy Clinic, is concerned about the prospects for making the vaccine widely available in nations where cervical cancer rates are highest.
"If we don't initiate this vaccine here too, there will be very little interest in having this vaccine used in developing countries," she said. In poorer countries, public health budgets tend to be minuscule, and women generally never receive Pap smears.
However, Sawaya suggested that it remains to be determined whether onetime screening and treatment might be more cost-effective than vaccinations in preventing cervical cancer deaths in these countries.
In the United States, Merck has indicated that it "will provide free vaccines to adults who are uninsured and who are unable to afford vaccines." Merck also is pursuing partnerships with the Gates Foundation and others to make the vaccine available in the most impoverished nations.
Read part 1.
UCSF Panel Discussion Airs Concerns, Hopes for New HPV Vaccines, Part 1 of 2
, September 20, 2006
Pediatrician Describes New Vaccines for Children
, September 5, 2006