Gardasil Provides No Benefit: CDC Study

The recent Gardasil study by the CDC claims that the vaccine has significantly reduced HPV infections. The authors’ claim bears little resemblance to the study’s results. Here’s an analysis demonstrating that, in reality, no conclusions can be drawn—that the study’s results are inconsistent, based on non-matched samples, and mixed the groups being compared.

Junked Science

Junked Science

by Heidi Stevenson

Recently, the mainstream news media was worked up about a study claiming that Gardasil has proven to be effective in preventing HPV (humanpapillomavirus) infections, and thereby, the implication that it will also prevent cervical cancer. However, careful perusal of the study shows something entirely different—that the vaccine provides no discernible benefit.

Lest there be any doubt about the study’s claim, the title is “Reduction in Human Papillomavirus (HPV) Prevalence Among Young Women Following HPV Vaccine Introduction in the United States, National Health and Nutrition Examination Surveys, 2003–2010″. Clearly, the point the authors wanted to get across is that Gardasil, the HPV vaccine in question, works.

It sounds outrageous to claim that a study with that title doesn’t live up to its promise. However, the authors focused the spotlight on only a small portion of their results to give that impression. When placed into proper perspective, the only legitimate conclusion to be be drawn is that Gardasil does not provide any benefit.

The study, financed by the Centers for Disease Control (CDC) relied on the National Health and Nutrition Examination Survey (NHANES), an ongoing CDC group of studies “to assess the health and nutritional status of adults and children in the United States.” The researchers of this study looked at data from two sampling periods, 2003-2006, the “pre-vaccine era”, and 2007-2010, the “post-vaccine” era, because vaccinations were started in 2007 (with a few exceptions at the end of 2006).

The vaccine is designed to prevent infections of four types of HPV: types 6 and 11, which cause genital warts, and types 16 and 18, which can cause cervical cancer—though in the vast majority of cases, they are naturally healed by the body and cause no known problems.

The result that the authors and news media have heavily promoted is that the 14-19 year old age range saw a reduction between the two time periods of 11.5% to 5.1% in types 16 and 18 HPV infections. That does sound significant. It seems to indicate that Gardasil has reduced the incidence of infection by 56 percent, a highly significant amount.

Different Ages, Different Results

However, by their own estimation, the sample size is too small to make any real conclusions. Yet, that’s precisely what they did, as their title clearly demonstrates! But the truth is significantly worse than that little slip. The vaccine was not given only to 14-19 years olds, it was also given to young women up through age 26. So what were the results in the age ranges of 20-24 and 25-29?

Ages 20-24 saw an infection rate increase from 18.5% to 19.9%—1.08 times more infections!

Ages 25-29 saw an infection rate increase from 11.8% to 13.1%—1.11 times more infections!

If the Gardasil vaccine had worked as claimed, wouldn’t there have been an infection reduction in those two age groups, too? Though they weren’t vaccinated as frequently, many young women did get it. Therefore, if there’s a reduction in HPV infections that can be attributed to the vaccine in 14-19 year olds, then surely there would be a reduction in ages 20-29, albeit smaller since fewer young women were vaccinated than teens. Instead, there was an increase!

Mixing Ages

No information was provided about how long after vaccinations the interviews and examinations were done. It appears that there was no consistency, that some may have been interviewed 6 months after vaccination, while others could have been interviewed 3 or 4 years later. For example, a girl might have been vaccinated in early 2007 at age 16, but not interviewed until she was 20 in 2010. That would put her in a different age range.

A large percentage of the girls who were in the 14-19 age group when vaccinated would have been in the 20-24 age range when questioned by NHANES. So that would also serve to decrease the percentage of 20-24 year olds infected with types 16 & 18 HPV—certainly not result in the increase this study shows. The same logic can be used for the next age range, 25-29.

Therefore, the groups are not discretely separated, as the authors would seem to imply.

Oversampled Group

Another anomaly could explain the discrepancy between the results of girls aged 14-19 and those 20-29. The sampling done between 2007 and 2010 was different for girls aged 14-19. According to the study:

To increase the precision of estimates, NHANES oversampled certain subdomains. In NHANES 1999–2006, Mexican Americans, blacks, low income white and others, and adolescents aged 12–19 years were oversampled. In 2007–2010, Hispanics, non-Hispanic blacks, and low income white and others were oversampled. Because adolescents were not oversampled in 2007–2010, there was a reduced number of individuals aged 14–19 years.

In the 2007-2010 timeframe, Hispanics, non-Hispanic blacks, and low income people were oversampled … except among adolescents! In other words, the groups were not similar; they were intentionally made dissimilar. Did that make a difference? Perhaps—but we do not know. What we do know is that the researchers may have been comparing apples with oranges in teenaged girls between the two timespans.

Researchers’ Conflict of Interest

So why didn’t the authors tell the whole story? That seems quite obvious. They’re all CDC employees. The CDC has been promoting Gardasil very heavily. They not only financed the study, their own employees produced it. In an agency that was headed by Julie Gerberding, who left to take a highly lucrative position as vice president of Merck’s vaccine division, it isn’t difficult to see that no one who does anything counter to the prevailing vaccines-for-everything-for-everyone is likely to have a future with the CDC. As one research fellow with the agency stated on

Whether you become an FTE (full time employee) depends exclusively on politics, not on your hard-work and accomplishments.

The study that promotes the claim that Gardasil has reduced HPV infections has done nothing of the sort. In fact, it may provide better evidence for a contention that it has increased infection rates. After all, only one of the three age groups involved actually appeared to have a reduced rate of HPV infections. Let me clarify that I am not making that claim, as I do not believe that this study comes close to demonstrating any valid conclusions. However, such a claim would hold every bit as much validity as what the authors concluded.


There are four highly significant concerns with the results of this study:

  • The authors acknowledged that the sample size was inadequate.
  • The results were anomalous. All of the three age groups, 14-19, 20-24, and 25-29, should have had similar results. That is, they should all have shown an increase or decrease in infection rates. Yet they most assuredly did not.
  • The groups were not distinct from each other, so that age ranges between vaccination and examination could result in a subject starting out in one age range, but being examined after entering the next age range.
  • The 14-19 age group was not oversampled for the 2007-2010 timespan, which means that group is not homologous with the 14-19 2003-2006 group.

The authors are all employed by the CDC, which financed the study and actively promotes the Gardasil vaccine. The fact that they have presented the results in a highly biased manner is clear. It would appear that the study was spun to give the impression of a certain result, with little concern for whether the data actually supports it. It wouldn’t be out of line to label the study as pseudo science or junk science.

Here is a copy of the results presented by the study: