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HPV vaccine efficacy against against invasive HPV-related cancers

The evidence of the HPV vaccine efficacy against cancer is becoming overwhelming. A new article shows that the vaccine prevents invasive HPV-related cancers. People are always asking me when we will get a cancer vaccine — this is it.

I continue to write about the HPV vaccine because it is simply one of the best ways to prevent cancer. Drinking GMO-free, organic, blueberry-soy-kale smoothies is not going to prevent cancer, no matter how much you believe the nonsense on the internet. On the other hand, the HPV vaccine is going to prevent cancer, and we have evidence of its efficacy.

Let’s take a look at the newest peer-reviewed research.

Happy young women who don’t have to worry about HPV-related cancers because of the vaccine. Photo by Joel Muniz on Unsplash

All about HPV and HPV vaccines

I know I cut and paste this section to every article I write about HPV vaccines, but it’s the first step to HPV vaccine myth debunking. Some readers may be coming here for the first time, and they ought to know just how the HPV vaccine prevents cancer. 

However, I try to update this section when necessary with new information about either the disease or the vaccine. If you’ve read this section 47 times, just skip down to the next section where I discuss the key point of this article.

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 strains, 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 46,000 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 46,000 cancers a year in the USA alone. The HPV vaccine prevents becoming infected by HPV, which means you are protected from these cancers.

Photo by Melissa Askew on Unsplash

HPV vaccine efficacy paper

In a paper by Matti Lehtinen, Karolinska Institutet, Stockholm, Sweden, published in BMJ Open on 30 December 2021, Lehtinen and his team examined randomized cohorts of HPV-vaccinated and non-vaccinated women who were enrolled in clinical trials for the HPV vaccine in Finland. There were 3,341 women in the vaccinated groups and 16,526 in the unvaccinated control groups. Both groups were followed from 2007 or 2009, depending on the group, and ended in 2019.

This is what the researchers found during the 11-12 years of follow-up:

  • They identified 17 HPV-positive invasive cancer cases (14 cervical cancers, 1 vaginal cancer, 1 vulvar cancer and 1 tongue cancer) in the non-HPV-vaccinated cohorts.
  • They found no cases in the HPV-vaccinated cohorts.
  • HPV typing of diagnostic tumour blocks found HPV16 in nine cervical cancer cases, HPV18, HPV33 and HPV52 each in two cases and HPV45 in one cervical cancer case. The vaginal, vulvar and tongue cancer cases were, respectively, positive for HPV16, HPV52/66 and HPV213.
  • Intention-to-treat vaccine efficacy against all HPV-positive cancers was 100% (95% CI 2 to 100, p<0.05).

Some of you will look at these numbers and wonder what’s the point. There were “only” 17 HPV-positive cancers in the non-vaccinated cohort. Except that’s a rate of 1 cancer case per 1000 unvaccinated versus 0 per 1000 vaccinated women. And this is after 10 years, and because cancer risk increases by age, we don’t know what it will be like at 20 or 30 years.

Preventing 1 in 1000 cancer risk is worth it, especially since are a lot of good ways to reduce the risk of cancer.

At any rate, this is one more chunk of powerful evidence that the HPV vaccine has substantial efficacy against some terrible cancers. Given the vaccine’s incredible safety profile (probably one of the safest vaccines ever), this should be on the priority list of everyone who doesn’t want to get these HPV-related cancers.

Let’s conclude this article with the author’s conclusion:

The excellent VE (vaccine efficacy) against HPV-positive cancers now documented from a randomised study setting, it is an important evidence of the long-term impact of HPV vaccination. It indicates that prevention of a sexually transmitted infection and associated cancer by prophylactic vaccination are doable and paves the way for the WHO’s initiative on the elimination of cervical cancer.


Michael Simpson
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