By Sarah Cimperman, N.D., Vol. 17, No. 5.
In June 2006, the United States Food and Drug Administration (FDA) approved the Gardasil® vaccine, designed to prevent infection by certain strains of the human papillomavirus (HPV). That same month, a federal advisory panel on immunization practices recommended that all eleven- and twelve-year-old girls receive the vaccine.
But before girls and their parents can make informed decisions, it is important to understand the possible risks and potential benefits of Gardasil, as well as alternative options for increasing immunity and reducing risk of infection.
There are more than one hundred strains of the human papillomavirus, and at least forty can be transmitted through sexual contact, affecting both men and women. According to the National Cancer Institute, fourteen of these sexually transmitted HPV strains have been associated with a high risk for developing cervical cancer. Two of these, 16 and 18, are associated with seventy percent of all cases.
According to the FDA, HPV infection is very common, and it is rare for HPV infection to lead to cervical cancer, especially in women under the age of thirty. In fact, ninety percent of cervical HPV infections become undetectable within two years. When cervical cancer is diagnosed, it is one of the most treatable cancers. According to the American Cancer Society, invasive cervical cancer diagnosed in its earliest stage has a five-year survival rate of ninety-two percent.
Gardasil, manufactured by Merck, is currently the only available vaccine against HPV, specifically strains 6, 11, 16 and 18. To measure the effectiveness of the vaccine, trials conducted by Merck assessed prevention of pre-cancerous lesions, not cervical cancer. Therefore, predictions about the ability of Gardasil to prevent cancer are speculation, as the majority of pre-cancerous lesions revert to normal without treatment and only a minority develop into cancer.
Merck researchers concluded that the vaccine was ninety-nine percent effective in preventing infection and pre-cancerous lesions caused by HPV strains 6, 11, 16 and 18 in women who had not been exposed to these viruses before immunization. The vaccine did not protect against infection or pre-cancerous lesions in women who had already been exposed to HPV. Because more than half of all men and women are exposed to HPV within one year of becoming sexually active, the vaccine is most effective when administered before the onset of sexual activity.
According to the CDC, approximately thirty percent of cervical cancers are caused by HPV strains not covered by Gardasil, and women who receive the vaccine are still at risk for cervical cancer. The vaccine does not treat existing HVP infections and does not prevent cervical cancer caused by existing infections.
The vaccine has only been tested by Merck, only for four years, and only in girls and women between the ages of nine and twenty-six. There is no long-term safety data about the vaccine and no information about its use in girls less than nine years old and in women above the age of twenty-six.
According to Merck’s clinical data, adverse effects after immunization most commonly included pain and inflammation at the injection site, fainting, dizziness, fever and nausea. Other side effects were rare, but some were very serious, including asthma, lymphadenopathy, Guillain-Barré syndrome, and systemic autoimmune disorders such as rheumatoid arthritis, juvenile arthritis, and systemic lupus erythematosis.
According to Merck, Gardasil has not been studied for its potential to cause cancer or birth defects. However, during clinical trials, women who became pregnant within thirty days of receiving the vaccine had more “serious adverse experiences during pregnancy,” including “congenital abnormality,” compared to women who received a placebo. Additionally, cases of acute respiratory illness were higher in the infants of breastfeeding women who had received the vaccine within the previous thirty days, compared to infants of breastfeeding women who received the placebo.