A Real Cancer Vaccine! What Are the Barriers to HPV Vaccination and Proposed Solutions?

7 Key Facts About HPV and the HPV Vaccine

1. HPV (Human Papilloma Virus) is a DNA virus with more than 100 subtypes. Cervical cancers: 99%; anal cancers: 88%, vaginal cancers: 70%, vulvar cancers: 43%, penile cancers: 50%, and oropharyngeal (mouth-throat) cancers: 70% are associated with HPV. Overall, approximately 5% of all cancers are associated with HPV.
2. The United States Food and Drug Administration (FDA) has approved 3 vaccines to prevent HPV infections:
   • Quadrivalent (four-type) vaccine (Gardasil)
   • Bivalent (two-type) vaccine (Cervarix)
   • 9-valent vaccine (Gardasil 9)
   
   When administered before exposure, these vaccines provide 100% protection against the HPV types they target.
3. Gardasil 9 prevents 90% of cervical, vulvar, vaginal and anal cancers.
4. The vaccines have been shown to provide full protection against the HPV types they target for 5 years, with effectiveness continuing for more than 9 years. Studies of their longer-term effects are ongoing.
5. Vaccination is strongly recommended for all girls aged 9-26 and all boys aged 9-21, but ages 11-12 are reported to be ideal for maximum effectiveness and safety. On October 5, 2018, however, the United States Food and Drug Administration (FDA) approved an additional application for the 9-valent human papillomavirus (HPV) vaccine Gardasil 9 to include women and men aged 27 to 45 under the additional approved application (for further details about this expanded approval, see here).
6. The HPV vaccine has a very good safety profile. Since it entered use in 2006, more than 200 million HPV vaccine doses have been administered worldwide, with no serious side effects reported so far.
7. Because HPV vaccines do not treat existing precancerous lesions and do not cover a small number of HPV types, routine HPV screening must continue.

The figure belowshows HPV-associated cancers:

HPV (Human Papilloma Virus)is one of the leading causes of cancer worldwide. It is responsible for 630.000 new cancer cases globally each year. Because HPV-related cancers also begin at younger ages, their impact in terms of years of life lost is considerable. Undoubtedly, the most important tool for reducing HPV-associated cancer incidence is the HPV vaccine, whose effectiveness and safety have been demonstrated in many studies. Despite its proven high effectiveness and safety profile, however, HPV vaccination rates fall far short of targets for various reasons.

Discovery of the Human Papillomavirus That Causes Cervical Cancer

In the 1970s, Harald zur Hausen proposed an idea no one had previously voiced: "Human papillomavirus (HPV) may be the cause of cervical cancer!". He believed this virus integrated its own DNAinto the DNA of cervical cells and used those cells to reproduce. To establish this, he needed to demonstrate HPV DNA in cervical cancer cells. Harald zur Hausen pursued the idea for more than 10 years by studying different HPV types. He encountered difficulties because only part of the viral DNA integrates into the host genome and HPV has more than 100 subtypes. Finally, in 1983, he demonstrated HPV DNA in cervical cancer biopsies and showed that HPV types 16 and 18 were the main causes of cervical cancer (HPV 16 and 18 were found in approximately 70% of cervical cancer biopsies).

- Related topic: From World War 2 to the Nobel Prize: Dr. Harald zur Hausen and the Discovery That HPV Causes Cervical Cancer (Detailed)

Barriers to HPV Vaccination and Proposed Solutions

Although barriers to HPV vaccination are multifactorial, they can essentially be grouped into 4 main categories:

1. Lack of Knowledge About HPV, HPV-Associated Diseases and the Characteristics of the HPV Vaccine

One of the most fundamental reasons HPV vaccination rates fall short of targets is lack of knowledge and failure to routinely explain and recommend the vaccine. In a 2014 study in Brazil, only 8.6% of participants said they had heard of the HPV vaccine. After being informed about it, 94% said they would get vaccinated or have their children vaccinated if it were covered by health insurance. In another North American study, 30% of parents cited the belief or information that "the vaccine is not necessary" as the main reason for not vaccinating their children. Among parents of boys, 23%, and among parents of girls, 13, cited their doctor's failure to recommend the vaccine as the main reason. Indeed, research identifies physician recommendation as one of the strongest modifiable factors in encouraging HPV vaccination.

2. Unfounded Concerns About the Vaccine's Safety Profile

Many parents cite safety concerns as the main reason for not having their children vaccinated against HPV. Yet according to World Health Organization data from March 2017, HPV vaccination had by then entered national immunization programs for 11-year-old girls in 71 countries and 11-year-old boys in 11 countries, with more than 200 million doses administered worldwide. No safety problem warranting changes to current recommendations for HPV vaccine use had been encountered. HPV vaccines have undergone various clinical trials, all of which confirmed their safety and effectiveness profiles. Health care providers should therefore not only recommend vaccination to parents but also explain its safety profile to correct misconceptions.

3. Cost

High cost is one of the most important barriers to increasing vaccination rates, especially in low- and middle-income countries. Considering the benefits, however, it is fair to describe vaccination as cost-effective. Indeed, given the expense of treating HPV-related cancers, studies have shown that HPV vaccination alone or vaccination combined with screening are cost-effective strategies. Many countries have consequently begun including HPV vaccination in health insurance coverage, substantially increasing uptake. In Brazil, for example, HPV vaccination increased from 3% to 92% of the target population (girls aged 11–13) when the health system began providing the vaccine.

4. Cultural Barriers

Cultural characteristics influence HPV vaccination programs, just as they affect screening programs. The fact that HPV is sexually transmitted can hinder communication and education about it. There is also an unfounded belief that HPV vaccination will increase adolescent sexual activity. Research, however, shows that HPV vaccination is not associated with increased sexual activity or sexual activity at an earlier age. Health care providers have an important role in dispelling these misconceptions and beliefs.

Another important factor affecting HPV vaccination rates is where vaccination takes place and the strategy used to deliver vaccines. Most other vaccines are given before age 2 and can therefore easily be administered during routine checkups. Because HPV vaccination occurs later, different strategies are needed. Studies have found better results with school-based vaccine delivery programs. Combining health care facility-based and school-based vaccination programs produces much better results.

The Power of Social Media in HPV Vaccination

According to mass communication theories, social media can create desired changes in attitudes and behavior across large populations. Although it is highly effective for communicating useful health advice, it can also spread misinformation. This is particularly important for vaccines, where public doubts about side effects may coexist with a substantial reduction in disease risk through mass immunization. HPV vaccination is among the most discussed vaccine topics on social media because its introduction coincided with the rise of these platforms.

A study found an association between the prevailing sentiment toward the HPV vaccine in a country and its nationwide HPV vaccination rates. This led to the conclusion that social media can influence people's vaccination decisions.

Social Media Content Analysis

Looking at social media messages about HPV vaccination, negative messages more often use personal stories to appeal to emotions, while positive messages more often use facts and statistical data to appeal to reason. Messages supporting vaccination generally focus on its benefits in preventing HPV, using factual, proven data, but rarely mention safety. Conversely, antivaccination narratives discuss adverse side effects without substantiated data and rarely mention effectiveness. Antivaccination messages also focus on conspiracy theories involving governments and the pharmaceutical industry.

Prevailing sentiment toward HPV vaccination differs significantly between social media sites. For example, supportive messages predominate on text-based Twitter, while antivaccination messages are more prominent on video-based YouTube.

The Effect of Social Media on HPV Vaccination Rates

Analyses show that most adults in the United States (62%) obtain at least one news item from social media daily, and 20% even use it as their primary news source. A study evaluating 274 million people exposed to more than 258.000 tweets found that the prevailing sentiment (positive or negative) about HPV vaccination in the messages people encountered was associated with national HPV vaccination rates. A 2018 study also found that participants tended to remember negative social media messages about HPV vaccination more readily. It further found higher child vaccination rates among those who remembered only positive messages.

Unfortunately, emotions generally prevail over reason. Although supportive social media messages have been shown to increase knowledge about the HPV vaccine, they have not been shown to increase vaccination rates. These findings are highly important for strategies to determine social media messaging about HPV vaccination. Health care providers and organizations should therefore communicate messages that appeal optimally to both reason and emotion to counter antivaccination messages on social media.

Conclusion

HPV (Human Papilloma Virus) is one of the leading causes of cancer worldwide. We have a highly effective preventive tool against it: a real cancer vaccine. Yet HPV vaccination, considered one of the most important developments in women's health, faces many barriers, including knowledge gaps, unfounded safety concerns, financial barriers and cultural obstacles. Appropriate strategies, including patient-physician communication and education, are needed to increase vaccination rates. Otherwise, the HPV vaccine will remain a highly effective but underused cancer prevention tool. Social media also has an important place here. It is essential to counter unfounded negative messages and to design messaging that appeals optimally to both reason and emotion.

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