I’ve written a billion (± 0.999 billion) times that one of the greatest of HPV vaccine benefits is cancer prevention. This really isn’t in question with cancer scientists, but as you know Dunning-Kruger anti-vaccine zealots think they know more than real scientists, and they look for any reason to bash the cancer-preventing vaccine.
And if you know anything about cancer, there are just a handful of ways to actually prevent any of the hundreds of different cancers. And the HPV vaccine is one of them.
Which leads us to this moment. Two recent studies have been published on HPV vaccine benefits – one supports the vast scientific consensus on HPV vaccine efficacy, the other is so poorly done, it tells us almost nothing about HPV vaccine effectiveness. Guess which one the anti-vaxxers will cherry-pick?
Let’s take a look at these studies, but first, as I always do with HPV vaccine benefits, I’ll start with a few words about HPV, the vaccine, and cancer.
All about HPV and HPV vaccines
I know I add this section to every article I write about HPV vaccines. It is updated almost every time with additional information about HPV or the vaccine. Moreover, there are readers who want to know more about HPV, and this section can help someone get up-to-speed quickly.
Genital and oral human papillomavirus (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. Of those 40 strain, most are fairly rare.
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:
In addition, there is some evidence that HPV infections are causally linked to skin and prostate cancers. The link to skin cancer is still preliminary, but there is much stronger evidence that HPV is linked to many prostate cancers.
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. The CDC also states that over 43,000 HPV-related cancers are diagnosed in the USA every year. It may be several times that amount worldwide.
There were two HPV vaccines on the world market before 2014. GSK, also known as GlaxoSmithKline, produced Cervarix, a bivalent (protects against two HPV strains) 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 strains) and 9-valent (against nine HPV strains) 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, protecting against HPV types 6, 11, 16, 18, 31, 33, 45, 52, and 58. It targets the four HPV strains found in the quadrivalent version, along with five additional ones that are linked to cervical and other HPV-related cancers.
Both versions of Gardasil are prophylactic, meant to be given to females or males before they become exposed to possible HPV infection through intimate contact.
Gardasil is one of the easiest and best ways to prevent a few dangerous and, to abuse the definition slightly, common cancers that afflict men and women. Without a doubt, the HPV vaccine prevents cancer.
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.
Let me sum this all up so that if you come away from this section with nothing else, you get this summary. HPV is a sexually transmitted disease. HPV causes 43,000 cancers a year in the USA alone. The HPV vaccine prevents becoming infected by HPV, which means you are protected from these cancers.
HPV vaccine benefits papers
The first paper, by Claire P Rees and published in the low impact factor Journal of the Royal Society of Medicine, examined the results of 12 randomized clinical trials of Cervarix and Gardasil. Their study is not characterized as either a systematic review or meta-analysis, both of which sit at the top of the hierarchy of biomedical research.
Those types of reviews attempt to review the data to find biases and “average” the data across many similar types of clinical studies to determine if there is a meaningful result, more powerful than any single clinical trial.
In the Rees et al. article, they take a very unusual method to show that the HPV vaccine has little effect on cervical cancer prevention. I want to examine their “conclusions,” which are a bit odd.
First, they claim that the clinical studies looked at cervical cancer exams 6-12 months after vaccination and stating that “there is evidence that vaccination prevents cervical intraepithelial neoplasia grade 1 (CIN1).” They then state that this isn’t clinically significant.
I have a few issues with this statement:
- CIN 1 is not clinically insignificant. Although it mostly resolves itself in 1-2 years, about 10% of CIN 1 cases progress to CIN 2, which is much more serious. Moreover, this claim just flabbergasts me – women who have a CIN 1 diagnosis worry about it.
- Most of the clinical trials last only 1-2 years, not for 20 or more years when we could ascertain the difference in CIN 2 or 3 diagnoses between vaccinated and unvaccinated populations.
- There have been numerous post-marketing studies that have shown statistically significant decreases in CIN diagnoses, thus HPV vaccine benefits, in the decade or so since the HPV vaccine was launched. Like this large one (reviewed here). Or this large study (reviewed here). Or this huge systematic review (analyzed here).
- The authors conclude that “this means that the trials may have overestimated the efficacy of the vaccine as some of the lesions would have regressed spontaneously.” Well, actually larger and longer-term studies, as I mentioned above, don’t show that. We know that HPV is linked to about 90% of cervical cancers, and if we can prevent the main HPV types that are linked to cervical cancer, then voila, the risk of cervical cancer drops. I don’t get authors like this who cavalierly dismiss those who remain at risk of cancer. It frustrates me.
- I can’t stop repeating something – HPV is not only linked to cervical cancer, but to many other types. Why do these authors not understand that the HPV vaccine benefits extend beyond preventing just one type of cancer?
Nevertheless, this study shows us nothing. There are better ones that actually establish HPV vaccine benefits between vaccinated and unvaccinated groups (plus showing us that there are no safety concerns).
Of course, the anti-vaxxers will cherrypick this poorly designed and poorly concluded study to say “gotcha.” Well, anti-vaxxers, you got nothing.
Better HPV vaccine benefits data
Recently published data from Public Health England (PHE) that examined the incidence of HPV infection from the licensure of the HPV vaccine through 2018. Here are their findings:
- PHE has conducted surveillance of type-specific HPV infections in sexually active 16-24-year-old females (undergoing chlamydia screening) since prior to the start of the national HPV vaccination program (with the HPV16/18 vaccine, Cervarix)
- the prevalence of HPV16/18 in sexually active 16-18-year-old females who were offered the vaccine at age 12-13 years has been less than 2% (compared to over 15% prior to the start of the vaccine program in 2008).
- in the most recent year, 2018, 10 years after the HPV vaccine was introduced, we detected no HPV16/18 infections in 16-18-year-olds (0% of n=584). This is an amazing result.
- the prevalence of HPV6/11 in 16-18 year-olds did not decrease until 2018, from 7-10% from 2010-2017 to 4.1% in 2018.
- the prevalence of HPV31/33/45 has also declined during the post-vaccination years, to the end of 2018, suggesting evidence of substantial cross-protection.
It is clear that few sexually active women are now getting infected with HPV which will lead to much lower rates of several cancers in the UK. Yes, some (but not 100%) of women who have HPV will experience no long-term effects. And yes, early screening will catch most CIN 1 cases, but that doesn’t mean that it won’t develop into more serious cervical cancers (see Note 1).
Once again with emphasis – it’s not just about cervical cancer in women. It’s about anal cancer, oropharyngeal cancer, and other cancers in both men and women.
The new paper that the anti-vaxxers are throwing about to “prove” that the HPV vaccine has no benefits to cancer prevention actually doesn’t “prove” anything. I can’t understand why someone published the article, but I keep saying that over and over with anti-vaccine articles (please comment below with the betting odds that it will be retracted).
And, of course, the anti-vaxxers are cherrypicking this one paper, while ignoring the hundreds of others on the HPV vaccine that completely and utterly contradict the conclusions. Even the darling of the anti-HPV vaccine world, Dr. Diane Harper, is on board with the HPV vaccine benefits.
I’d say “there is nothing to see here,” but I know better. The Rees article will be thrown around for years to come. Even if it’s retracted.
OK, gather around one more time. the HPV vaccine prevents cancer. And that’s settled science.
- This is an issue I constantly have with the anti-vaccine community – bad math. They constantly claim that a 1% risk of death from a vaccine-preventable disease, whether it’s measles or HPV, rounds down to 0%. They don’t consider the fact that vaccines actually round that down to nearly 0%. Then, they round up a 1 in a million risk for a severe reaction to a vaccine (and I’m not sure it’s even that high) to 100% risk. It’s frustrating and maddening. Of course, I don’t know if Rees et al. are anti-vaccine, but they should realize that their study will be misused by anti-vaxxers worldwide.
- Arbyn M, Xu L, Simoens C, Martin-Hirsch PP. Prophylactic vaccination against human papillomaviruses to prevent cervical cancer and its precursors. Cochrane Database Syst Rev. 2018 May 9;5:CD009069. doi: 10.1002/14651858.CD009069.pub3. [Epub ahead of print] Review. PubMed PMID: 29740819.
- Benard VB, Castle PE, Jenison SA, Hunt WC, Kim JJ, Cuzick J, Lee JH, Du R, Robertson M, Norville S, Wheeler CM; New Mexico HPV Pap Registry Steering Committee. Population-Based Incidence Rates of Cervical Intraepithelial Neoplasia in the Human Papillomavirus Vaccine Era. JAMA Oncol. 2016 Sep 29. doi: 10.1001/jamaoncol.2016.3609. [Epub ahead of print] PubMed PMID: 27685805.
- Bosch FX, Burchell AN, Schiffman M, Giuliano AR, de Sanjose S, Bruni L, Tortolero-Luna G, Kjaer SK, Muñoz N. Epidemiology and natural history of human papillomavirus infections and type-specific implications in cervical neoplasia. Vaccine. 2008 Aug 19;26 Suppl 10:K1-16. doi: 10.1016/j.vaccine.2008.05.064. Review. PubMed PMID: 18847553.
- Castle PE, Pierz A, Stoler MH. A systematic review and meta-analysis on the attribution of human papillomavirus (HPV) in neuroendocrine cancers of the cervix. Gynecol Oncol. 2017 Dec 13. pii: S0090-8258(17)31548-2. doi: 10.1016/j.ygyno.2017.12.001. [Epub ahead of print] Review. PubMed PMID: 29248196.
- Rees CP, Brhlikova P, Pollock AM. Will HPV vaccination prevent cervical cancer?. J R Soc Med. 2020 Jan 21: 141076819899308. doi: 10.1177/0141076819899308. [Epub ahead of print] PubMed PMID: 31962050.
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