Cancer Gone Viral: HPV vaccine hesitancy defies logic
Cancer HPV Vaccine

Cancer Gone Viral: HPV vaccine hesitancy defies logic

Dr. Talia Henkle
Dr. Talia Henkle

In 10 seconds? The wide administration of the Human Papillomavirus (HPV) vaccine has slashed cases of cervical cancer by almost 90%. However, public health officials are still fighting stigma and misinformation to improve those rates even further and prevent HPV-associated cancers in men as well.

What’s the story? When it comes to cancer, we know that prevention is key; it just makes sense. It’s undoubtedly preferable to never get cancer in the first place than to get a cancer diagnosis and spend time, money, and energy hoping you’ve caught it in time for a cure. Luckily, with HPV-associated cancers, prevention has never been easier with the invention of the HPV vaccine (marketed as Gardasil® which covers 9 strains, or Cevarix which covers 2), which has proven widely successful in preventing many types of cancer for both men and women (with no crazy diet or exercise routine needed!) But misinformation and stigma have dissuaded some parents from getting their kids vaccinated and stunted the vaccine’s life-saving potential.

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OK, tell me more about this HPV vaccine. Sure, I will! The vaccine design itself is very simple. Anatomically, HPV is a circle of DNA packaged inside a sphere made of proteins named L1 and L2. Researchers at the US National Cancer Institute discovered that if they produced a bunch of L1 proteins in the lab, they would self-assemble into a microscopic sphere that closely resembles the HPV (AKA virus-like particles). Of the 200+ strains of HPV, about 14 cause cancer (with 2 of the 14 causing around 80% of cases). In the latest form of the vaccine, virus-like particles made from L1 proteins from 9 different strains are mixed together, providing protection against the deadliest strains of HPV!

That’s it? Is it that simple? The last but essential step is mixing the virus-like particles with a standard substance that helps kick the immune response into gear–an adjuvant. Virus-like particles are made of pure protein, harmless floating specks which would usually be ignored by our immune system. But when they are mixed with an adjuvant (aluminum salts for Gardasil®), the immune system will leap into action and produce tons of antibodies against the virus-like particles–protecting us from HPV infection and, of course, cancer down the line. It’s not entirely clear how adjuvants boost our immune response, but they seem to help keep the virus-like particles from getting washed away from the site of injection before an immune response can form, and also may trigger some local immune-boosting signals.

Got it. So who is this vaccine for? The most recent HPV vaccine (the one that covers 9 HPV strains) was approved in 2014 for men and women ages 9-45 years old. Since HPV is so common, most people become exposed to HPV shortly after they first become sexually active. And the vaccine can only prevent HPV infection–not cure it! So, the best way to be protected from HPV-associated cancers (mostly cervical cancer in women and head/neck cancer in men) is to get vaccinated before you become sexually active. But 9-year-olds do not have the agency to decide to get vaccinated for themselves.

Why does that matter? Well, that means parents are tasked with deciding whether to vaccinate their children. And instead of focusing on the vaccine’s crucial role in preventing cancer, the focus somehow turned to the HPV’s connection with sexual activity–putting many parents on edge and leading to a vocal chorus of misinformation regarding the HPV vaccine’s safety and necessity. In fact, a 2016 study showed that parents who chose not to vaccinate their kids cited safety concerns and lack of necessity as their top reasons why.

Why parents choose to refuse the HPV vaccine for their children Source: Beavis A, et al. J of Adol Health. 2018:63(5);652-656

Well, are there safety concerns? The most common side effect of the vaccine is a pain in the injection site, which, while never fun, is only temporary and usually mild. Interestingly, compared to vaccines that are made from attenuated viruses (weakened viruses that can infect cells but not make us sick), and which are mandated for many public schools, virus-like particles should put parents more at ease as they are essentially just lifeless shells that help our immune system block HPV infection in the future.  And when compared to the pain and suffering HPV-associated cancers could cause down the line, I’d say some arm pain is well worth it! So, if you want to take real evidence-based steps against cancer…make sure you and your loved ones (and their kids) get the HPV vaccine!


A global challenge

While cervical cancer rates have been slashed in high-income countries where screening and vaccines are widely available, the rest of the world is still struggling.

In 2016, the Global Alliance for Vaccines and Immunization (GAVI) decided to sponsor HPV vaccination in the 72 lowest-income countries.

One of the issues is, that compared to other vaccines, the HPV vaccine is pretty expensive ($10.50/dose vs $1.50/dose for the MMR vaccine), and it is recommended to have three doses (although this is changing due to studies showing 2 doses to be equally effective). (Also, can we quickly compare what ‘expensive’ looks like for preventive measures versus million-dollar personalized cancer treatments…)

Experts worry that even with reduced vaccine prices through organizations like GAVI, the increased demand for the vaccine worldwide and limitations in manufacturing and supply will challenge effective dissemination to low-income countries...with Merck's corporate greed (the owners of Gardasil) to blame.  

Dr. Talia Henkle has distilled 3 of research papers saving you 10.5 hours of reading time.


The Science Integrity Check of this 3-min Science Digest was performed by Flávia Oliveira Geraldes.



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