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.