Unmet needs in HPV vaccination strategies

There are unmet needs for implementing human papillomavirus (HPV) vaccination strategies, according to a recent study published in Cancer Medicine.

Worldwide, cervical carcinoma is the fourth most common cancer in women aged 15 to 44 years, and over 75% of cases are diagnosed at advanced clinical stage. In 2020, the World Health Organization reported over 0.6 million new cases and over 0.34 million deaths from cervical carcinoma.

HPV16 and 18 infections have been linked to more than half of high-grade cervical carcinomas. HPV is transmitted through sexual contact and often clears up spontaneously, but there is a significant risk of infection developing into chronic and precancerous lesions that may lead to cervical cancer.

Vaccination is the most effective method of preventing HPV. To reduce cervical carcinoma risk, girls aged 9 to 14 years should receive a careful combination of high-coverage, affordable HPV vaccination.

Investigators conducted a review to characterize challenges, attitudes, and practices toward HPV vaccination, as well as associated research gaps. Databases evaluated for literature on HPV vaccination since 2015 include Medlineplus, PubMed, and Embase.

Search terms used included “HPV” AND “vaccination,” “HPV vaccination” AND “delivery strategies,” and “HPV vaccination” AND “coverage.” Eligible literature included research articles, case reports, national health authorities' guidelines and advisories, surveillance reports, and press releases from international health organizations.

Eligibility criteria included describing HPV vaccination and cervical cancer prevention strategies, gray literature, published in English, and published between 2015 and 2023. Exclusion criteria included providing irrelevant information, not being peer-reviewed, and unavailable full text. Three investigators independently reviewed articles and documents.

There were 30 articles included in the final analysis, conducted across 11 countries. The primary outcomes of most included studies were HPV vaccination knowledge, delivery strategies, determinants, and challenges.

Global strategies for preventing cervical cancer aim to have 90% of female individuals receive full HPV vaccination by the age of 15 years. The World Health Organization has recommended national immunization programs include HPV vaccines, and multiple countries including the United States have adapted their programs to this recommendation.

Vaccines are often delivered at health care facilities, outreach initiatives, or a combination of these 2 methods. Either school-based or facility-based approaches are being implemented in high-income countries, while a combination of these approaches is often implemented in low-income countries.

Facility-based approaches include a 2-dose regimen delivered in a health care facility such as a health center or clinic. In the United States, this approach led to a 73% first dose rate of administration and 50% second dose in 2022.Additional strategies in the United States to improve vaccination rates include community campaigns and eliminating cost barriers.

School-based delivery involves administering the vaccine to children in school settings and had a coverage rate of approximately 99% in Brazil. A combination of this method with facility-based approaches was observed in Switzerland, with a rate of 74% for the first dose and 71% for the final dose. This success has been attributed to easy and free vaccine access, coordinated delivery, and increased knowledge.

Facility-based strategies have a coverage rating above 70% among 36% of adapters, school-based strategies among 30%, and mixed strategies among 53%. Challenges to vaccinations strategies included health system challenges, vaccine challenges, and individual challenges.

Delivery strategies must be developed to effectively provide vaccination, and internet and social media platforms should be considered for spreading messages encouraging vaccination against HPV. Coverage should be high and equitable to prevent dropout. 

Additionally, supporting vaccines which provide better protection may further reduce HPV incidence. Adverse events, including fever, nausea, headache, myalgia, pain, swelling, dizziness, erythema, pruritus, and bruising may increase vaccine hesitancy, making it important to not improperly spread information about these events.

Available data has indicated efficacy from a single dose vaccine in preventing HPV, but more research is necessary. Additionally, new vaccinations to manage HPV subtypes should be developed, and children should be vaccinated at age 9 or 10 years when possible.

This review indicated challenges in HPV vaccination that require interventions to improve vaccine uptake. Investigators concluded effective implementation of interventions can lead to the introduction of an effective approach for high vaccination coverage.

Reference

Aggarwal S, Agarwal P, Gupta N. A comprehensive narrative review of challenges and facilitators in the implementation of various HPV vaccination program worldwide. Cancer Med. 2023;00:1-14. doi:10.1002/cam4.6862