HPV Prevention With Gardasil
In October of 2005, the Food and Drug Administration approved use of the vaccine Gardasil for use in girls and women ages 9 to 26. The vaccine works by preventing infection by four strains of the human papillomavirus, or HPV, the most prevalent sexually transmitted disease. Other types of the HPV virus cause genital and skin warts. The HPVs that convey a high risk of cervical cancer are contracted by up to an estimated 70 per cent of sexually active women. Cervical cancer is the 11th most common cancer among women in the US; an estimated 9,710 new cases are reported each year, which kills 3,700 women, with hundreds of thousands more casualties worldwide. Acting FDA Administrator Dr. Andrew von Eschenbach said the vaccine will have “a dramatic effect” on the health of women around the world.
Most women would test positive for the presence of HPV at some time in their lives, but its presence on the skin is not inherently a problem. The problem comes when the skin where the virus is sitting suffers a “microtrauma,” allowing the virus to invade through the wound to below the outer skin layer. Even then, the virus is usually picked up and eliminated by the immune system. In a small number of cases though, the virus makes its way into a healthy cell at the basal skin level, insinuates itself into the cell’s nucleus, and begins to replicate with it. That will develop into a cancer, although it is thought to take at least three years for the abnormality to be significant enough to be detected in a Pap test.
The virus can go through the same process in other parts of the body, and in males as well, but is less likely to because the surface of the cervix has thinner skin and is more likely to suffer tiny injuries, such as during intercourse and even tampon use.
Gardasil, manufactured by Merck & Co. Inc., protects against the two types of HPV responsible for about 70 percent of cervical cancer cases. The vaccine also blocks infection by two other strains responsible for 90 percent of genital wart cases. Clinical trials showed Gardasil prevented 100 percent of cervical cancer related to the two HPV strains (16 and 18, although the FDA indicates types 6 and 11 are also prevented) in women who had not been previously infected, Merck said. It also prevented 99 percent of the cases of genital warts caused by the two other strains. Gardasil is given as a series of three shots over a six month period, which cost about $360 or more.
There is much discussion about who will cover the cost of the vaccine if it is to be widely distributed. According to Merck’s website, the company “has created a new patient assistance program for vaccines. Through this new program, Merck will provide free vaccines to adults who are uninsured and who are unable to afford vaccines. Merck vaccines, including GARDASIL, will become available through this program in the third quarter of 2006.”
The FDA has agreed that the vaccine appears very safe. However, it is not known how long its protection will last (some experts believe three to four years) or if women will have to receive booster shots later in life. Merck has agreed to monitor its long-term effectiveness.
Right wing groups have expressed disagreement with suggestions that the vaccine be made widely available to women of all ages. They believe that immunizing teenagers will encourage sexual activity.
The target age for receiving Gardasil was initially low because the vaccine works best when given to girls before they begin having sex and run the risk of HPV infection. The vaccine may not protect people already infected and may increase their risk of the kind of lesions that can lead to cervical cancer, the FDA has said. However, in May of 2006, researchers announced that the new cervical cancer vaccine will provide protection for older women as well as young girls.
