HPV vaccine safety – another massive scientific study (UPDATED)

In a 2013 study of over 1 million girls, the overall HPV vaccine safety for teenage girls was reaffirmed. There appear to be no links between serious adverse events and the HPV vaccines. This is in line with numerous other large size epidemiological studies of HPV vaccines.

Let’s take a look at the HPV vaccine safety that is supported by this trial.

All about HPV and the vaccine

I know, I’ve written about this vaccine over 100 times – however, this might be your first bit of research into the HPV vaccine, so it’s important to get a brief overview of HPV and the vaccines. If you’ve read this before, just skip to the next section if you want.

Genital and oral human papillomavirus (HPV) are the most common sexually transmitted infections (STI) in the USA. There are more than 150 strains or subtypes of HPV that can infect humans, although only 40 of these strains are linked to a variety of cancers. HPV is generally transmitted from personal contact during vaginal, anal or oral sex.

Although the early symptoms of HPV infections aren’t serious, those infections are closely 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:

(All data is for the USA only.)

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 with respect to cancer. According to the CDC, roughly 79 million Americans are infected with HPV–approximately 14 million Americans contract HPV every year. Most individuals don’t even know they have the infection until the onset of cancer. About 27,000 HPV-related cancers are diagnosed in the USA every year.

There were three HPV vaccines on the market. GSK, also known as Glaxo SmithKline manufactured Cervarix, a bivalent vaccine which has been withdrawn from the US market. Merck manufactures Gardasil9, a 9-valent vaccine, along with Gardasil, a quadrivalent HPV vaccine.

The study

This large study, by Arnheim-Dahlström et al., published in the respected medical journal, BMJ (once known as the British Medical Journal), reviewed HPV vaccine safety in Danish and Swedish girls.

The size of this study was impressive. The authors reviewed the records of 997,585 girls, aged 10-17, to determine their HPV vaccination status. They determined that 296,826 of those girls received the quadrivalent HPV vaccine, a total of 696,420 doses of the vaccine. Look at that carefully, 696 thousand doses. That number is so high, that even minor adverse events may be uncovered. Except, unsurprisingly, none were found.

Arnheim-Dahlström et al. also supports another large study published in 2012, which included nearly 200,000 young females who had received the vaccine, and found that the vaccine was only associated  with same-day syncope (fainting) and skin infections in the two weeks after vaccination.

The researchers examined patient records for 53 different diagnoses requiring hospital or specialist care, including blood clots, neurological diseases, and autoimmune diseases such as type 1 diabetes between immunized and non-immunized groups. The limited the study to 180 days post-immunization (except for thromboembolic events, which they limited to 90 days). Out of the 53 adverse events, 24 were eliminated from the study because <5 events were observed in the vaccinated group (which would become statistically impossible to analyze).

Of the remaining 29 adverse events, the results are shown in the table below.

Rates of adverse events according to quadrivalent human papillomavirus (qHPV) vaccination status, cohort of adolescent girls aged 10-17 years in Denmark and Sweden, October 2006-December 2010
Rates of adverse events according to quadrivalent human papillomavirus (qHPV) vaccination status, cohort of adolescent girls
aged 10-17 years in Denmark and Sweden, October 2006-December 2010

Out of these 29 events, 26, including all of the neurological incidents, showed no statistical difference in risk between the vaccinated and unvaccinated group. Three, Behcet’s syndrome, Raynaud’s disease, and type 1 diabetes (all autoimmune associated diseases) showed small, but statistically significant higher risks in vaccinated individuals. However, because of several factors, including random response time post-vaccination and the fact that the incidence rate for the three mirrored what is found in the general population of girls of this age, the authors determined that their was no evidence of a causal relationship.

According to the authors,

Although significantly increased rate ratios were initially observed for three outcomes, further assessment showed no consistent evidence for a plausible association; firstly, these risk signals were relatively weak, as assessed by prespecified criteria, and, secondly, no temporal relation between vaccine exposure and outcome was evident.

The authors then concluded that,

this study identified no safety signals with respect to autoimmune, neurological, and venous thromboembolic events after the qHPV vaccine had been administered.

The lead author of this study, Dr. Lisen Arnheim-Dahlström, associate professor at Karolinska Institutet’s Department of Medical Epidemiology and Biostatistics stated, “you could see our study as part of a societal alarm system, and as such it did not alert us to any signs that HPV vaccination carries a risk of serious adverse events. We will, of course, be continuing to monitoring HPV vaccination in terms of both this and its efficacy over time.”


This study was supported by a grant from the Swedish Foundation for Strategic Research and the Danish Medical Research Council. The funding bodies had no role in the study design; the collection, analysis, and interpretation of the data; the writing of the article; and the decision to submit it for publication. All authors are independent from the funding agencies.

Additionally, the anti-vaccine world has passed off false claims that Lisen Arnheim-Dahlström, a renowned researcher, has been bought off by Merck, Sanofi and probably the Skeptical Raptor. Although she did receive grants in the past from Merck and Sanofi, but not the Skeptical Raptor, they were for unconditional studies, which are grants given with no expectation of results.

Furthermore, I find it offensive that anti-vaccine radicals think that scientists can be bought off with a grant. I think it’s an indication of their quality of moral foundation, that they themselves can be bought off by the anti-vaccine disinformation campaign (very well funded by various groups), so everyone else is.

It’s just a form of ad hominem argument that is laughable at best. They lack any valid evidence for their attacks on Gardasil, so what’s left are logical fallacies. Of course, Dr. Lisen Arnheim-Dahlström has a PhD, during which she studied HPV and cervical cancer. No further defense of her is required.

Summary on HPV vaccine safety

Once again, we have evidence, in the form of a impressively large retrospective epidemiological analysis, that none of these serious adverse events were more common in the vaccinated group than in the unvaccinated group. HPV vaccine safety is supported by real scientific evidence.

The HPV vaccine is demonstrably safe. The HPV vaccine prevents cancer. The HPV vaccine saves lives.

Editor’s note – this article was first published in October, 2013. It has been updated for style and formatting along with fixing broken links. Also, a discussion of Dr. Lisen Arnheim-Dahlström was required.


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!