Gardasil safety supported by a large study of 200 thousand young women

I regularly write about Gardasil safety and effectiveness, because I consider the HPV vaccine one of top 100 greatest medical inventions over the past century or so. We have so few ways to prevent cancer, despite the nonsense pushed by pseudoscientists like the brainless Food Babe. And one of the best ways to prevent cancer is getting the HPV vaccine to prevent HPV related cancers.

I originally wrote this article around 5 years ago, but it needed updating on several issues since things have changed on this website. But why do I care about maintaining a 5-year-old article about Gardasil safety? Because this is one of the seminal articles about Gardasil safety, one that is important to anyone’s understanding of the subject.

Let’s get into it.

All about HPV and Gardasil

Many of you have read this section an enormous number of times, however, for some of the readers of this blog, this article might be their first bit of research into the human papillomavirus (HPV) vaccine. Thus, it’s important to get a brief overview of HPV and the vaccines. If you’ve read this section before, just skip to the next section if you want.

Genital and oral  HPV infections are the most common sexually transmitted infections (STI) in the USA.  HPV is generally transmitted from personal contact during vaginal, anal or oral sex.

It’s important to note that there are more than 150 strains or subtypes of HPV that can infect humans – however, only 40 of these strains are linked to one or more different cancers. Although the early symptoms of HPV infections aren’t serious and many HPV infections resolve themselves without long-term harm, HPV infections are causally linked to many types of cancers in men and women. According to current medical research, here are some of the cancers that are linked to HPV:

These are all dangerous and disfiguring cancers that can be mostly prevented by the HPV cancer vaccine. If you’re a male, and you think that these are mostly female cancers, penile cancer can lead to amputation of your penis. Just think about that guys.

HPV is believed to cause nearly 5% of all new cancers across the world, making it almost as dangerous as tobacco in that respect. According to the CDC, roughly 79 million Americans are infected with HPV – approximately 14 million Americans contract a new HPV every year. Most individuals don’t even know they have the infection until the onset of cancer. Accordingly, about 27,000 HPV-related cancers are diagnosed in the USA every year.

There were two HPV vaccines on the world market before 2014. GSK, also known as GlaxoSmithKline manufactured Cervarix, a bivalent vaccine. It has been withdrawn from the US market (although available in many other markets), because of the competition from the quadrivalent (immunizes against four different HPV subtypes) and 9-valent (against nine subtypes) Gardasil vaccines.

Merck manufactures Gardasil, probably the most popular HPV vaccine in the world. The first version of the vaccine, quadrivalent Gardasil, targets the two HPV genotypes known to cause about 70% of cervical cancer and two other HPV genotypes that cause genital warts. In Europe and other markets, Gardasil is known as Silgard.

The newer Gardasil 9, approved by the FDA in 2014, is a 9-valent vaccine. It targets the four HPV genotypes in the quadrivalent version, along with five additional ones that are linked to cervical and other types of cancer. Both versions of Gardasil are prophylactic, meant to be given before females or males become exposed to possible HPV infection through intimate contact.

Gardasil is one of the easiest and best ways to prevent a few deadly cancers that are related to HPV. It is definitely a cancer-preventing vaccine.

(Just a quick note. There are actually two cancer-preventing vaccines. Along with the HPV vaccines, the hepatitis B vaccine is also important for the prevention of some cancers.  The vaccine prevents hepatitis B viral infections. Chronic hepatitis B infections can lead to liver cirrhosis or cancer. Liver cancer is actually one of the few cancers in the USA where the incidence has increased over the past few years. And if you follow the anti-vaccine rhetoric, you know the hepatitis B vaccine is almost as controversial as the HPV vaccine.)

Currently, in the United States, the Advisory Committee on Immunization Practices (ACIP) recommends that preteen girls and boys aged 11 or 12 are vaccinated against HPV. The immunization is also recommended for teenage girls and young women up to the age of 26 who did not receive it when they were younger, and teenage boys and young men up to the age of 21.

200 thousand woman Gardasil safety study

A study published in Archives of Pediatrics & Adolescent Medicine affirms the safety of the HPV quadrivalent vaccine. This version of the vaccine prevents infection by human papillomavirus subtypes 16 and 18 which cause approximately 70% of cervical cancers, along with most HPV-related anal (95% linked to HPV), vulvar (50% linked), vaginal (65% linked), oropharyngeal (60% linked) and penile (35% linked) cancers. Remember, there is strong clinical evidence that the incidence of HPV infections have declined since the launch of the HPV vaccine and the subsequent steady rate of HPV vaccination.

The large study, which included nearly 200,000 young females who had received the vaccine, found that the vaccine was only associated with same-day syncope (fainting) and skin infections in the two weeks after vaccination. These findings support other large studies that also found the vaccine safe and an appropriate strategy to prevent cervical cancers. The authors stated that “this study did not detect evidence of new safety concerns among females 9 to 26 years of age secondary to vaccination with HPV4.”

In an article in Science News, lead author Nicola Klein, MD, PhD, co-director and research scientist at the Kaiser Permanente Vaccine Study Center in Oakland, Calif, stated that,

…taking into account all the analyses, subanalyses and relevant medical record reviews, an independent safety committee noted that there may be an association between HPV4 vaccination and same-day syncope, as well as skin infections during the two weeks after immunization.

Fainting is not an unexpected result of vaccinations reported the authors, because injections of all types are correlated with fainting.

The study’s strengths, a large, ethnically diverse population who received a total of nearly 350,000 HPV4 doses; an integrated health care delivery system (Kaiser-Permanente) that assured complete or near-complete medical information and follow-up; and a “pre-specified, validated, clinically meaningful system to categorize all outcomes.”

This study is powered in a way to find causal links to vaccinations since patients are closely monitored before and after the vaccinations. The results strongly support the fact of Gardasil safety.

Summary of Gardasil safety

Let’s repeat what was found in this study.

  • 350,000 doses of Gardasil given.
  • The only adverse reactions were fainting, an expected outcome from any needle injection, and skin infection, another expected (and preventable) outcome.
  • So, in a well-controlled study, where the patients could be observed carefully in a modern healthcare environment, no dangerous adverse events were observed.

The HPV vaccine, Gardasil, prevents cancer, that is well-established. And it’s extraordinarily safe.

So, who are you going to believe, some random rumors and anecdotes published on the internet by random pseudoscience websites? Or a huge, scientific study published in the Journal of the American Medical Association, one of the premier medical journals in the world? Unless you prefer quack medicine, the answer should be easy.

Editor’s note – this article was first published in September 2013 (back in the early days of this website). Because the article is still relevant and important to the discussion about Gardasil safety, I decided to do a fairly thorough rewrite to fix some broken links, to copyedit, and to update the formatting.

Laughably, back then I was still doing the old-fashioned double-space after the end of each sentence. WordPress didn’t like it, so I decided to break a 40-year-old habit. This article had a few double-spaces still around. Amusingly, the double-space habit is the subject of some debate across the internet – imagine that?


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The Original Skeptical Raptor
Chief Executive Officer at SkepticalRaptor
Lifetime lover of science, especially biomedical research. Spent years in academics, business development, research, and traveling the world shilling for Big Pharma. I love sports, mostly college basketball and football, hockey, and baseball. I enjoy great food and intelligent conversation. And a delicious morning coffee!