The HPV Vaccines Work


I have blogged before on the Human Papillomavirus (HPV) vaccines, in particular Gardasil. After reviewing the data, I came to the conclusion that this vaccine is essentially safe and does what Merck advertises what it does. The epidemiological data is pretty hard to argue with, and the safety of the vaccine also seems pretty well established. Some readers did not like my conclusions, but that what the data leads me to conclude.

I am not for mandating the vaccine. HPV is acquired by having sex, and young girls can decide for themselves if they are going to have sex and if they should get vaccinated. Health care professionals should definitely encourage sexually active men and women to be vaccinated.

Now a new study provides further evidence that HPV vaccines are effective. A new paper in the Journal of Infectious Diseases by Lauri E. Markowitz, Susan Hariri, Carol Lin, Eileen F. Dunne, Martin Steinau, Geraldine McQuillan, and Elizabeth R. Unger reports that the prevalence of four strains of HPV that can cause cervical cancer, has decreased more than 50% among females aged 14-19 since the introduction of the vaccine in 2006. This is strongly suggests that the vaccine is effective and should result in a reduction in cervical cancer deaths in the long run.

In this study, Markowitz and others analyzed HPV prevalence data from two periods of time: the vaccine era (2007–2010) and the prevaccine era (2003–2006). These data came from National Health and Nutrition Examination Surveys. The prevalence of HPV was determined by detecting HPV in vaginal swab samples from females aged 14–59 years; there were 4150 provided samples in 2003–2006, and 4253 provided samples in 2007–2010.

The results of these surveys showed that among females aged 14–19 years, the prevalence of those HPV strains against which the vaccine was made (HPV-6, -11, -16, or -18) decreased from 11.5% in 2003–2006 to 5.1% in 2007–2010. This is a decline of 56%, and statistically speaking, the confidence intervals for these findings were very high, indicating that these data are quite trustworthy.

Markowitz and her group concluded, “Within 4 years of vaccine introduction, the vaccine-type HPV prevalence decreased among females aged 14–19 years despite low vaccine uptake. The estimated vaccine effectiveness was high.”

Is HPV a problem? Clearly it is. Consider the following data: Approximately 79 million Americans, most in their late teens and early 20s, are infected with HPV, and every year about 14 million people become newly infected.

“This report shows that HPV vaccine works well, and the report should be a wake-up call to our nation to protect the next generation by increasing HPV vaccination rates,” said CDC Director Tom Frieden, M.D., M.P.H. “Unfortunately only one-third of girls aged 13-17 have been fully vaccinated with HPV vaccine. Countries such as Rwanda have vaccinated more than 80 percent of their teen girls. Our low vaccination rates represent 50,000 preventable tragedies – 50,000 girls alive today will develop cervical cancer over their lifetime that would have been prevented if we reach 80 percent vaccination rates. For every year we delay in doing so, another 4,400 girls will develop cervical cancer in their lifetimes.”

According to CDC, each year in the United States, about 19,000 cancers caused by HPV occur in women, and cervical cancer is the most common. About 8,000 cancers caused by HPV occur each year in men in the United States, and oropharyngeal (throat) cancers are the most common.

Clearly HPV is a health problem, and the fact that there is a vaccine available that works is a good thing.

Some news reports quote experts who are troubled that “only” 49% of females aged 13-17 have received a dose of the vaccine, and “only” 32% have received all three doses recommended by the manufacturer. However, the same survey found that only 50% of females aged 14-19 have had sex. Therefore, it is probable that these data suggest that the vaccine is reaching exactly the people who need it and not those who do not.

The words of the Family Research Council seem rather prescient in this regard: “Not every female “needs” the HPV vaccine — those who practice sexual abstinence until marriage and fidelity within marriage have a negligible risk of infection. Those women (and men) who abstain are, at the same time, protecting themselves from other strains of HPV not covered by the vaccine, other STDs, unintended pregnancy, and a range of emotional and relationship problems.”

The HPV vaccine works. If you need it, get it. If you don’t, then don’t. That’s my take.

Gardasil: Does it Work and Is it Safe?


Gardasil is a vaccine made by Merck and it stimulates the immune system to recognize and attack various strains of the human papilloma virus.  Human papilloma virus causes warts, but particular strains of it also cause a sexually transmitted disease called genital warts, which are the beginnings of cervical carcinoma.  One-quarter-of-a-million women die each year, globally, from cervical cancer.

This vaccine has been the center of several political and policy debates.  The Gardasil debate has definitely caught the attention of the country. During the Republican presidential candidate debates, on September 12, 2011, candidates Congressman Ron Paul (TX) and Congresswoman Michele Bachmann (MN) attacked fellow candidate Texas Governor Rick Perry for his executive order to mandate the vaccination of Texas school children.  The next day, Congresswoman Bachmann said, on NBC’s Today Show, “I will tell you that I had a mother last night come up to me here in Tampa, Fla., after the debate and tell me that her little daughter took that vaccine, that injection, and she suffered from mental retardation thereafter.”  As much as I like Michelle Bachmann, that was a pretty astounding statement about this vaccine.

As the father of three girls, two of whom are in high school, believe me, I understand the issue. Parents want to make such significant choices for their families on their own without Big Brother doing it for them. Nevertheless, health care professionals and epidemiologists, who see the 250,000 deaths each year from cervical cancer want to see the herd immunity against human papilloma virus (HPV) to go up so that the carrier rates of this virus will fall. Mandating the vaccination is one way to do that. “Not so fast,” say many parents who have worked very hard to teach their children sexual ethics that are at odds with those of the culture. “We have taught our girls to save sex for marriage and prevented them from being exposed to the oversexed pop culture of modern youth and now you want us to vaccinate them against the rotten fruits of that culture?” It is a fair question.

What gets lost in all this is that the vaccine, Gardasil, made by the pharmaceutical giant Merck, based in Whitehouse Station, New Jersey, does exactly what the company says it does. There have been some movements on the web to discredit Gardasil. For example, The Truth About Gardasil is raising money to make a full-length film about the dangers of Gardasil. Other such campaigns are also found on the web.

On the other hand, journal Nature has summarized the results of the Gardasil trials, Future I and Future II. These trials enrolled 17,600 women across the Americas, Europe, and Asia-Pacific who received the vaccine between December 2001 and May 2003.

The results from these studies are pretty clear and positive. Gardasil, in these women, was 100% effective in preventing genital warts, the precursor to CIN or cervical intraepithelial neoplasia. While there were women diagnosed with CIN or AIS (adenocarcinoma in situ), the numbers were too low to draw any firm conclusions. Gardasil was not able to get rid of HPV in women with established infections at the time of injection, which is no surprise, since it is a vaccine and not a treatment.

Gardasil contains a mixture of peptides (polymers of amino acids) from four different strains of HPV: strains #6, #11, #16 and #18. Strains #16 & #18 are responsible for 70% of all cervical cancer cases globally. Strains #6 and #11 cause 90 percent of all genital warts. Therefore, Gardasil contains a mixture of the most troublesome strains of HPV. There are other strains of HPV that cause cervical cancer. For example, long-term infections with HPV strains #31 and #45 can also cause cervical cancer. Therefore, Gardasil does not prevent all types of cervical cancer. However, in those women who were vaccinated with it, it seems to prevent cervical cancer, at least over the course of 9-12 years.

If lots of women die each year from cervical carcinoma, then surely we should rejoice that many of these women who have been vaccinated will not contract cervical cancer. Men can also contract penile cancer from HPV. Therefore, this vaccination is also being marketed and given to men as well. Mind you, unchecked promiscuity has plenty of other risks and these risks should not be minimized. However, if some women will not die from HPV as a result of Gardasil, it seems to me that this is a good thing.

What about the side effects of Gardasil that are touted on sites like The Truth About Gardasil? In the Future I and Future II studies, there were no serious side effects reported. This is from a global population of young women. Therefore, the side effects mentioned on The Truth About Gardasil website might be 1) particular to those women, which certainly deserves much more research; 2) unrelated to the vaccine; or 3) related to the vaccine but only tangentially.

Should these side effects be ignored? Not at all. The CDC runs a web site where reactions to Gardasil and all other vaccines are monitored known as the Vaccine Adverse Event Reporting System (VAERS). According to this site, there were 12,424 reported adverse events after about 23 million doses of vaccine between June 2006 and December 2008. That’s an adverse reaction rate of 0.054% per dose. Folks, that’s pretty low. Also, if you consider that the vast majority of adverse reactions are really minor (fainting, headaches, sores at the site of the injection that resolve over time), this constitutes a pretty small number of adverse reactions.  The problem is the 32 deaths, but even here, the deaths are the result of embolisms (clots in the bloodstream) and these are caused by other things that are probably not related to the vaccine. The 32 deaths means that Gardasil has a 1 / 1,000,000 deaths per dose rate. This is rate that is so low that is seems very unlikely that the vaccine is causing the deaths, and the proximity of the death to the vaccine is coincidental at best.

Where does this leave us?  The vaccine does what it says it does – prevent cervical cancer from the two major strains of HPV. It is not a cure for it. It is, as far as we can tell to date, safe. The rate of deaths after a Gardasil injection are not higher than immediate deaths in general and that seems to indicate that the deaths are not related to the vaccine. Also, the severe adverse reaction rates are well within the safety levels expected for a good vaccine.

Regardless of your views on whether or not Gardasil should be mandated, you must say that it works and that it is safe. The data support such a conclusion. Therefore, other statements about Gardasil should be about policy and not about the safety or efficacy of the vaccine. Gardasil works and is safe.

For studies on Gardasil, see the following:
1. Future II Study Group N. Engl. J. Med. 356, 1915–1927 (2007).
2. Garland, S. M. et al. N. Engl. J. Med. 356, 1928–1943 (2007).
3. Paavonen, J. et al. Lancet. 374, 301–314 (2009).
4. Future I/II Study Group BMJ 341, c3493 (2010).
5. Munoz, N. et al. J. Natl Cancer Inst. 102, 325–339 (2010).
6. Lehtinen, M. et al. Lancet Oncol. 13, 89–99 (2012).
7. Kreimer, A. R. et al. Lancet Oncol. 12, 862–870 (2011).
8. Donovan, B. et al. Lancet Infect. Dis. 11, 39–44 (2011).
9. Brotherton, J. M. L. Lancet Infect. Dis. (in press).
10. Brotherton, J. M. L. et al. Lancet 377, 2085–2092 (2011).
11. Australia Dept. Health and Aging. National HPV vaccination data for girls aged 15 in 2009. National HPV Vaccination Program (2011).
12. Shearer, B. D. HPV Vaccination: Understanding the impact on HPV disease. http://www.nccid.ca/files/Purple_Paper_Note_mauve/PP_34_EN.pdf (2011).
13. Widgren, K. et al. Vaccine 29, 9663–9667 (2011).
14. Department of Health, UK. Annual HPV Vaccine Coverage in England in 2010/2011.
15. Centers for Disease Control and Prevention Morbid. Mortal. Weekly Rep. 60, 1117–1123 (2010).

Disclosure: I own no stock in Merck, and was neither paid by Merck for this article, nor contacted by them at any time in the writing of this article. These conclusions are mine, and therefore, if you disagree with me, please do not call me a paid shrill for Merck because I am not. Instead, please simply address where in the published data you think I have misunderstood, and I will do my best to respond.