We keep reading false claims about Gardasil, like some link between the HPV vaccine and multiple sclerosis. It is important that we, those who support vaccines, keep focusing on the huge studies that support the facts about the safety of the vaccine.
Despite the established effectiveness of the HPV vaccine in preventing the HPV infection and subsequent HPV-related cancers, the internet rumors about the dangers of the vaccine sometimes feel like it wins the day.
Remember, despite what you read on pseudoscience website or from anecdotes on the internet, there are really only a few ways to prevent cancer. Don’t smoke. Don’t drink alcohol. Stay out of the sun. Keep a very healthy (read low) weight. And get your HPV (and hepatitis B) vaccines.
This post is going to discuss a seminal article about the safety of vaccines – an epidemiological study of over 2 million young women to determine the incidence of neurological disorders in HPV-vaccinated vs. unvaccinated groups. This powerful study tells us one thing – that the continued claims about Gardasil causing all these weird neurological issues is not supported by unbiased, scientifically analyzed, peer-reviewed articles. And head’s up, there appears to be no evidence supporting a link between the HPV vaccine and multiple sclerosis.
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.
HPV vaccine and multiple sclerosis – the study
In a study published in the Journal of the American Medical Association, researchers assessed the correlation between the HPV vaccine and multiple sclerosis (MS). They looked at the risk of MS and other similar central nervous system disorders after receiving the quadrivalent version of Gardasil. The study utilized a large patient population, and the results pretty clear:
- This cohort study examined 3.9 million women and girls, including 790,000 who had received the Gardasil vaccine. The total amount of Gardasil doses was over 2 million.
- The study looked at the medical records of all females aged 10 years to 44 years in Denmark and Sweden, followed up from 2006 to 2013.
- After excluding those who had already been diagnosed with multiple sclerosis or other demyelinating neurological conditions, the researchers tracked all first-time diagnoses of optic neuritis, neuromyelitis optica, transverse myelitis, and acute disseminated encephalomyelitis, which are other, non-multiple sclerosis demyelinating diseases.
- Because the first symptoms of some of these diseases may take up to 24 months to manifest, the researchers examined the medical records for a full two years after the last HPV vaccine dose (in the vaccinated group), comparing it to the rates in unvaccinated subjects.
- The researchers found no increased risk of multiple sclerosis or any other demyelinating disease in the HPV vaccinated group.
- Ironically, the researchers actually found that the vaccinated group had a risk of 6 multiple sclerosis cases per 100,000 per year, while the unvaccinated group had a risk of 21.5 MS cases per 100,000 per year. No, it is not likely that the HPV vaccine prevents or lowers the risk of MS (or other demyelinating diseases), we can only conclude that the vaccine does not increase the risk.
Let’s be incredibly clear – in this huge study of a relatively homogenous population (which reduces many confounding factors), there was no difference in risk of multiple sclerosis and other demyelinating diseases between HPV vaccinated and unvaccinated groups. This should put this myth about this particular risk out to pasture.
About epidemiological studies
One of the constant tropes pushed by the anti-vaccine crowd is that “there are no clinical studies that show the safety of Gardasil in vaccinated and unvaccinated groups,” which is demonstrably untrue. In fact, some of the better studies, are post-marketing studies that continue to examine safety and efficacy of all drugs, including vaccines. These post-marketing studies are not included in vaccine package inserts, which are not exactly good sources of information about vaccines.
Epidemiological studies, such the cohort study that we discussed above, are powerful types of research that rank high in the hierarchy of clinical evidence. In fact, in supporting or rejecting a hypothesis of causality, like a link between HPV vaccine and multiple sclerosis, a cohort study can provide very powerful evidence, especially if the study is large, like the 3.9 million women included in this study.
In a world of reviewing scientific evidence, well done, well-analyzed studies that reject a link between Gardasil and various neurological conditions are powerful and difficult to refute. Unless you rely on cherry-picking data that support your personal beliefs about Gardasil, then nothing I could present would be acceptable.
Let me keep beating the drums here. HPV vaccine prevents HPV infections in large populations, even at the low vaccine uptake we’re observing. HPV vaccine prevents a large number of serious and dangerous cancers, one of the very few tools we have to prevent real cancers. And the vaccine is safe.
There is simply no link
There are no justifications for not preventing cancer by getting this vaccine. Get Gardasil for your kids. Get it for yourself if you’re a young adult. It’ll save your life.
Editor’s note: This article was originally published in January 2015. Like another article I just updated on Gardasil, this one needed some thorough copyediting and fixing of dead links. I consider this study to be one of the most important in dismissing some of the most specious and outrageous claims about the HPV vaccines.
- Scheller NM, Svanström H, Pasternak B, Arnheim-Dahlström L, Sundström K, Fink K, Hviid A. Quadrivalent HPV vaccination and risk of multiple sclerosis and other demyelinating diseases of the central nervous system. JAMA. 2015 Jan 6;313(1):54-61. doi: 10.1001/jama.2014.16946. PubMed PMID: 25562266.
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