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Home » HPV vaccine adverse events – study of 11 years of use in Australia

HPV vaccine adverse events – study of 11 years of use in Australia

The anti-vaccine crowd loves to push claims about awful HPV vaccine adverse events, scientific evidence has never supported it. Fortunately, numerous large studies have shown over and over and over that HPV vaccine adverse events are rare and not serious. 

Now, we have a robust new study from Australia, one of the first countries to provide the vaccine free to its citizens, that has followed HPV vaccine adverse events for over 11 years. And just to cut to the chase, they didn’t find anything serious, but I’ll go into detail below.

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 new readers who want to know more about HPV, and this section can help someone get up-to-speed quickly. 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 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.

Australian HPV vaccine adverse events study

In an August 2020 study, published in Vaccine, Dr. Anastasia Phillips, et al. examined Australian surveillance data for quadrivalent human papillomavirus vaccine over 11 years. The researchers analyzed HPV vaccine adverse events as reported to the Australian HPV vaccination register.

During those 11 years, over nine million doses of the HPV vaccine were administered in Australia. Of those, the researchers found 4,551 observed adverse event reports. They determine that there was a crude reporting rate of 39.8 adverse events per 100,000 doses of the vaccines.

They also found that:

  • The rate for syncope, or fainting, was 29.6 cases per 100,000 doses in 12-13-year-old males and females during an “enhanced surveillance” period.
  • The syncope rate was 7.1 per 100,000 doses in the other surveillance periods.
  • The rate of anaphylaxis was about 0.32 per 100,000 doses.
  • The researchers found other reported adverse events including autoimmune disease, postural orthostatic tachycardia syndrome (four cases), primary ovarian insufficiency (12 cases with variable times post-vaccination), Guillain-Barré syndrome (four cases), complex regional pain syndrome (four cases), and venous thromboembolism (three cases). However, all of these were reported at extremely low rates, and the authors did not find any unexpected patterns that would suggest a causal association between the vaccine and these adverse events. Moreover, these low numbers are approximately the same as what we would find in a general, non-vaccinated population.

The authors concluded:

Over an 11-year period, reporting rates of AE following 4vHPV
administration in Australia were consistent with data from similar
surveillance systems internationally and did not reveal any new or
concerning safety issues. However, during a period of enhanced
surveillance implemented to monitor introduction of the vaccine
to adolescent males in addition to females, syncope was noted to
occur at a higher rate in younger adolescents than previously
observed. AESI, except for syncope, were reported rarely following
4vHPV and no new or concerning patterns were identified. This
comprehensive analysis further contributes to the large body of
existing data affirming the safe post-marketing profile of 4vHPV
vaccine in both males and females and the value and characteristics of long-term spontaneous reporting systems in monitoring
vaccine safety.

In other words, the researchers found no concerning issues with HPV vaccine adverse events except for syncope, a condition that is frequently observed with all vaccines or procedures that use needles such as blood draws.

So, once again, we have powerful research that the HPV vaccine is safe. Can we move on to other things? Probably not, give me a few weeks, and there will be another large study that includes thousands or millions of participants that will show the vaccine is safe and effective.



Michael Simpson
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