HPV vaccine prevents cervical cancer – “strong evidence”

In a newly published article, strong evidence supports the claim that the HPV vaccine prevents cervical cancer. This obliterates the anti-vaccine argument that we don’t know if the HPV vaccine works. Well, we knew that it would work, since it blocks the cancer-causing human papillomavirus, but now we have more direct data.

Of course, the old feathery dinosaur could not pass up the opportunity to wave more real science (as opposed to the anti-vaccine pseudoscience) under the noses of the vaccine deniers. So, here we go.

The HPV vaccine prevents cervical cancer. Hopefully, she got the vaccine. Photo by Brooke Cagle on Unsplash.

All about HPV and HPV vaccines

I know I add this section to every article I write about HPV vaccines, even though I consider removing it. However, it is usually updated frequently 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. So, you can skip this section, if you’ve read it for the 47th time.

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.

Science journals – they show that the HPV vaccine prevents cervical cancer.

HPV vaccine prevents cervical cancer article

In an article by Mélanie Drolet et al., published in The Lancet on 26 June 2019, researchers found robust evidence that the HPV vaccine significantly decreases the risk of precancerous cervical lesions as well as anal-genital warts. 

The meta-analysis (considered the pinnacle of the hierarchy of biomedical research) examined data on 60 million individuals over nearly 10 years. The analysis included 65 studies published from February 2014 through October 2018. This new analysis updates a study published in 2015 by the same researchers. 

They found the following:

  • 5-8 years after receiving the HPV vaccine, the prevalence of HPV 16 and 18 decreased by 83% among girls, age 13-19.
  • During the same time period, the prevalence dropped by 66% in women, age 20-24.
  • Again, during the same time period, the prevalence of cervical intraepithelial neoplasia grade 2+ (known as CIN2+, see Note 1) decreased by 51% in girls, age 15-19.
  • The prevalence of CIN2+ decreased by 31% in women, age 20-24.
  • The prevalence of CIN2+ did not decrease in countries with low HPV vaccine coverage.
  • The researchers found that with high vaccination coverage, the impact of the HPV vaccine produced substantial herd immunity. They discovered statistically significant decreases in HPV 31, 33, and 45 among girls, ages 20 and younger.
  • Notably, they found a 67% decrease in anal-genital warts in girls, ages 15-19, and a 54% decrease in women, ages 20-24.
  • Additional evidence in support of a powerful herd effect from HPV vaccination, the rate of anal-genital warts in boys, ages 15-19, decreased by 48%, and in men, ages 20-24, 32%. 

The authors wrote:

Our results provide strong evidence of HPV vaccination working to prevent cervical cancer in real-world settings, as both the cause (high-risk HPV infection) and proximal disease endpoint (CIN2+) are significantly declining. In terms of global policy implications, these results reinforce the recently revised position of WHO recommending HPV vaccination of multiple age cohorts of girls, and provide promising early signs that the WHO call for action on cervical cancer elimination might be possible if sufficient population-level vaccination coverage can be reached.

In an accompanying editorial, also published in The Lancet, Silvia de Sanjose, MD, Ph.D., and Sinead Delany-Moretlwe, MBBCh, Ph.D., stated that greater vaccine coverage is critical to herd immunity, given that the disease burden accounts for more than 80% of deaths attributable to HPV-related cancers in low-income and middle-income countries. 

de Sanjose and Delany-Moretlwe stated that:

This new analysis by Drolet and colleagues provides compelling evidence for HPV vaccine efficacy on all outcomes explored and for almost all age strata, and confirms their previous analysis. It also confirms a greater and faster direct impact and herd effects in countries with multiple age-cohort vaccination and high vaccination coverage, compared with countries with single age cohort vaccination or low vaccination coverage.

Obligatory cute animal photo. This is a modern dinosaur, as opposed to the old dinosaur who wrote this article. And it is irrelevant to the HPV vaccine prevents cancer. Photo by Zdeněk Macháček on Unsplash.

Summary

Once again, we have data, piled upon previous evidence, that the HPV vaccine prevents cervical cancer. This is approaching settled science

And let’s remember that HPV is not just about cervical cancer – the virus is directly linked to other dangerous and deadly cancers that attack both men and women. Not only does the HPV vaccine prevent cervical cancer, but it also prevents numerous other cancers.

And in case you are wondering, the HPV is also very safe. That’s also settled science. 

There are very few ways to prevent cancer. The HPV vaccine is one of the best ways. 

Notes

  1. CIN2+ indicates the histology of cervical lesions. In this case, CIN2+ encompasses CIN 2, CIN 3, adenocarcinoma in situ (AIS), and cancer. This is an indicator of a serious pre-cancerous or cancerous lesion in the cervix. A CIN2+ diagnosis requires treatment to preserve the health of the patient.

Citations

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!