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Home » Japanese HPV vaccine study – new data destroys anti-vaxxer tropes

Japanese HPV vaccine study – new data destroys anti-vaxxer tropes

If you have been paying attention to the pages about the Japanese HPV vaccine, you would know about some controversies there. The whole experience there is the basis of numerous vaccine denier memes and tropes that have always been inaccurate. Now we have some scientific data that makes some of those lies quite funny.

Let’s take a look at this new data.

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.

Japanese HPV vaccine 01
Based on the data, most of these Japanese women have received the HPV vaccine. Photo by bady qb on Unsplash.

The Japanese HPV vaccine situation

Let’s take a quick look at the history of the Japanese HPV vaccine because it’s quite complicated. And, of course, it was the basis of annoying myths about the HPV vaccine.

In June 2013, the Japanese Health Ministry withdrew its recommendation for the HPV vaccine for children and teens there. They did this because they noticed 176 adverse events that followed the HPV vaccine. 

In other words, 0.0019% of cases, or about 1.9 events in 100,000 Gardasil vaccinations showed a temporal link to some adverse events, though not a causal link. Moreover, this is a number so small that it’s pretty close to impossible to affix any statistical significance to it, and it probably is significantly below the rate observed in the general population in controlled epidemiological studies.

Importantly, they only withdrew recommending it, quite a bit different than the anti-vaxxer claim that “Japan banned Gardasil.” Moreover, the health ministry agreed, at the time, that there probably was not a causal relationship between the vaccine and the adverse events.

This decision is one of the most egregious examples where correlation isn’t even close to causation.

Of course, this action by the Health Ministry lead to the inevitable lawsuits from attorneys looking to make money from a specious and statistically insignificant claimed link between the adverse events and the HPV vaccine.

Finally, a very poorly designed Japanese study that attempted to show a link between the HPV vaccine and neurological issues added fuel to the fire against the vaccine. Of course, that study was retracted because it was poorly designed and was pure pseudoscience.

Japanese HPV vaccine 02
Obligatory Japanese cuisine photo. Nothing to do with the Japanese HPV vaccine. Photo by Vitchakorn Koonyosying on Unsplash.

The Japanese HPV vaccine study

Results from a prospective cohort study of young Japanese women who received the HPV vaccine were presented to the Society of Gynecologic Oncology 50th Annual Meeting on Women’s Cancer which was held in Honolulu, Hawai’i in March 2019 (see Note 1). 

In this study, HPV screening and type-specific HPV testing were performed on 2,493 Pap test specimens collected from Japanese women aged 20 to 21 years during the period covering 2014 to 2017. Study participants provided HPV vaccination history through the completion of a questionnaire provided to the participants.

Here are some of the key results:

  • For the years 2014 to 2017, HPV vaccination rates were 28.6%, 74.8%, 76.7%, and 80.0%.
  • The prevalence of HPV 16/-18 infection (the subtypes most linked to cervical cancer) was 1.3% in 2014, 0.5% in 2015, 0.4% in 2016, and 0% in 2017. These are all statistically significant.
  • In 2014, the most prevalent strains were HPV-52, HPV-16, and HPV-56. HPV-52, HPV-51, and HPV-58 were most prevalent in 2017.

This study makes some very important observations. First, the Japanese HPV vaccine uptake has increased despite the Health Ministry error – it seems higher than the uptake in the USA which has never withdrawn recommendations for the vaccine.

Second, HPV 16/18 has apparently disappeared (or it’s so rare that it can’t be detected). This is powerful evidence for the effectiveness of the vaccine.

Finally, the population of HPV strains has shifted to HPV-52, HPV-51, and HPV-58. Of course, the “newer” Gardasil9 protects against 52 and 58, so that will probably begin to reduce those subtypes.

This is wonderful news that contradicts a lot of the false claims of the anti-vaccine world. The Japanese HPV vaccine is safe and effective. And young women are still getting it.


  1. This was a meeting presentation which is at the lower end the hierarchy of biomedical research. I generally do not review meeting presentations and abstracts, but this study was fairly important and demands attention. I will revisit this study once it is published in a peer-reviewed journal so that I can make a more thorough examination of the study methods and 



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