The heated political arguments about the vaccination of children to prevent oral and genital cancers have become so charged that any thoughtful discussion of the potential risks and benefits of the vaccine now appears to be out of the question.
When the manufacturer of the vaccine initiated lobbying efforts to make the vaccine a requirement for school registration and enrollment, the objections became so widespread and vehement that those efforts were abandoned. However, the substantive issues and questions are too important. They should not be crowded out by the din being created by the politically motivated on both sides of the issue.
Almost 40 years ago the human papilloma virus, HPV, was found to cause a sexually transmitted disease. In 1985, epidemiological studies linked the virus to genital cancers of the cervix and vulva. As it turned out, there are more than 50 strains of this virus with some 10 of them considered oncogenic -- associated with an increased risk of cancer -- with two strains, HPV-16 and HPV-18, accounting for 70 percent of all cases of cervical cancer. In the last three decades, these oncogenic strains of HPV have also been shown to be causally related to cancers of the oral cavity, vulva, vagina, anus, rectum and penis.
Five years ago, a vaccine to protect against the effects of four of the oncogenic strains of the HPV most strongly associated with the increased risk of cancer was approved by the Food and Drug Administration. The vaccination protocol involves three inoculations given over a six-month period at a total cost of approximately $400.
To be effective, the vaccine must be given before HPV infection, so the FDA recommends vaccination before adolescence and the onset of sexual activity. Although the current suggested regimen for vaccination is for girls and boys beginning as early as 9 years old, according to the Centers for Disease Control and Prevention, less than a third of the original target group of adolescent girls have received three doses of the vaccine.
Because the vaccine only protects against four oncogenic strains of HPV virus, girls and women still require screening for the disease with a Pap smear -- the current gold standard for the detection of precancerous lesions and cancers of the cervix -- and/or a test for the presence of HPV virus. There are additional methods available to detect precancerous lesions in females and males which are office procedures that can be performed without anesthesia. The essential point is that current screening programs will have to be continued in those who are vaccinated.
There is no way of knowing what the long-term effects of administering HPV vaccines are in young children. Historically, data about other vaccines is not reassuring. The Salk polio vaccine was grown in monkey kidney cells, which later were found to be contaminated with another virus not identified before the vaccine had been administered to millions of children. Sixty years later, there are still debates about what the potential effects of that occult virus might be.
In the World War II, yellow fever vaccine was administered to military troops being sent to regions where yellow fever was endemic. It wasn't until long after the war was over that we learned that the egg-grown yellow fever vaccine was contaminated with an avian virus. Several studies were launched in the late '50s attempting to determine if the military personnel who received the yellow fever vaccine had suffered any significant diseases which could potentially be attributed to the contaminating virus, but logistical obstacles prevented the completion of those investigations.
There is still a great deal of work that needs be done to evaluate this new HPV vaccine. We don't know if it results in lifelong immunity for those vaccinated. We don't know if there is significant variability in the development of effective immunity to the vaccine. The unknown risks of the HPV vaccine deserve a thorough discussion -- especially since it is a very costly intervention, which does not eliminate the need for customary follow-up surveillance of the disease it is being administered to prevent.
The cancers it does prevent all have precursors, which may be diagnosed and treated, thereby lowering the risk of cancer. While a valid argument can be made that the use of the HPV vaccine is justified in third world countries where Pap smear screening and elimination of the premalignant lesions is not readily available, I believe that other strategies may be more appropriate for young girls and boys in the U.S., which will not expose them to potentially significant health risks.
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