The HPV Vaccine - Are You Confused?

In recent weeks, attitudes about the HPV vaccine have often shifted from fanfare to fear as newspapers, blogs and medical journals have inundated the media with conflicting opinions. While the public wants information about the vaccine in simple and clear terms, the potential benefits and limitations of this vaccine have been somewhat difficult to see in black and white. Some of the questions that have dominated the media about the vaccine are:

Is the vaccine safe? -- The recent concerns over Gardasil's safety have many parents worried. No doubt, adverse effects have to be carefully monitored to assure that the vaccine has a good safety profile. Being a parent myself, I can fully understand these concerns, but as a physician, I have had the opportunity to take a closer look at Gardasil's safety profile. So far, nearly 8 million doses of Gardasil have been administered and all adverse effects have been carefully analyzed by medical experts at VAERS (Vaccine Adverse Effects Reporting System), a branch of the CDC. So far, no common pattern of reports has emerged to show that the vaccine is directly responsible for any of the adverse effects reported. Therefore, both the FDA and CDC continue to find that Gardasil is a safe and effective vaccine with benefits far outweighing the risks.

Will the vaccine cause "Replacement disease?" -- The August 2008 issue of the New England Journal of Medicine voiced several concerns over the HPV vaccine. One of the concerns was that the protection Gardasil provides against the two major HPV strains would give the currently less dangerous HPV types an opportunity to grow stronger and cause disease more often. This phenomenon is called replacement disease. Replacement disease was seen, for example, when the vaccine Prevnar was introduced in 2000 to fight against respiratory disease caused by the pneumococcal bacteria in children. And, even though there were a few cases of the disease caused by types of pneumococci that were not covered by the vaccine, they were insignificant when compared to the millions of lives that were saved by the vaccine. With the HPV vaccine, there are currently a few reports alluding to the emergence of non-vaccine covered HPV types, but these have not been of any clinical significance.

When is the best time to vaccinate? -- revisited -- Public health treats populations, not individuals. Therefore, when making recommendations for a whole generation of American women, public policy makers have to take several factors into account in order to calculate the most cost effective way to obtain maximum benefits from a drug or vaccine. The HPV vaccine is preventive in nature, meaning that it can't cure existing HPV infections. Therefore, from a public health standpoint, it is best to administer the vaccine to 11-12 year old girls before their sexual debut, rather than later (catch-up vaccination is currently recommended between the ages of 13-26 years) when they may have already been exposed to the virus. This is also the time when middle school children go to their doctors or clinics to receive other recommended shots, making it an easier time to offer the HPV vaccine. Vaccinating girls at this age will give the best protection because it will reduce HPV related disease consequences later in life, including the unexpected potential for exposure due to events such as infidelity within a long term relationship or having new sexual partners after widowhood or divorce.

Will the vaccine affect natural immunity? -- Natural immunity to a particular disease is acquired when a person is exposed to the specific organism that causes the disease. Obviously, this involves considerable risk -- for example, in order to gain natural immunity from polio, one would become paralyzed in the process. Immunity acquired from the vaccine causes a person to produce antibodies without developing the actual disease in most cases. In the case of HPV, it is not clear if natural infections offer adequate protection for life, but studies have shown that the vaccine produces antibody levels which are nearly tenfold higher than antibody titers produced by natural infections. Whether this heightened immunity leads to stronger and longer effectiveness is not yet known.

Is it true that there's no proof that the vaccine will reduce the rate of cervical cancer? -- Very few HPV infections lead to cervical cancer, as over 90% of infections clear up on their own. Of those that persist, the lag time between acquiring an HPV infection and the development of cervical cancer is nearly 20 years. Therefore, the young women who are being vaccinated today have to approach the ages of 35-50, when cervical cancer peaks, before we will have conclusive results. However, there is enough scientific evidence to support the theory that the vaccine can prevent cervical cancer. Clinical trials look at cancer surrogates -- conditions which when left alone will invariably progress to invasive cervical cancer -- as end points of the study. In the case of the HPV vaccine, they look for significantly abnormal cells or precancerous lesions in women who have been vaccinated. The vaccine has been found to prevent the development of these abnormal cells by the HPV types that are covered by it. Thus, it has been predicted that the vaccines will prevent cervical cancer. Obviously, no one can predict with complete accuracy how the vaccine will work in the "real world" over the next several decades. It is a leap of faith to some extent, but a leap that most of us are willing to take because of our trust in the "miracles" of medicine that have served us so well over the years.

©2008 Dr. Shobha S. Krishnan, M.D.

Author Bio
Dr. Shobha S. Krishnan, M.D., is a Staff Physician at Columbia University's Barnard College Health Services. A board certified gynecologist and family practice physician, she has also worked as a surveillance physician for the federal Centers for Disease Control and Prevention. Prior to joining Barnard, she was in private practice for 10 years. In addition, Dr. Krishnan has worked as a physician at the Institute on Aging and as Chief Resident in the Family Practice Department at St.Vincent Hospital, Indianapolis. Her new book: The HPV Vaccine Controversy: Sex, Cancer, God and Politics -- A Guide to parents, women, men and teenagers is scheduled to be published on August 30, 2008 by Greenwood Publications. The book presents the most up to date information about the vaccine without the influence of pharmaceutical companies or other interest groups.