HPV Vaccine

Intro

The human papillomavirus (HPV) vaccine protects against infection from HPV strains responsible for most cases of cervical cancer, as well as many anal, penile, oropharyngeal, and vulvar cancers. It also prevents genital warts. HPV vaccination is considered one of the most effective cancer prevention tools in modern medicine.

Key Points

HPV and cancer: HPV types 16 and 18 cause ~70% of cervical cancers worldwide.
Vaccination impact: Proven to reduce precancerous lesions and cancer rates where widely adopted.
Recommendations: WHO, CDC, and ATAGI recommend vaccination for adolescents, ideally before sexual debut.
Safety: Extensive monitoring shows the HPV vaccine is safe, with mostly mild side effects (sore arm, fever, headache).

Background

HPV is a common sexually transmitted infection; most people are exposed at some point. Persistent infection with high-risk HPV types can lead to cancer.

Development: The first HPV vaccines (bivalent and quadrivalent) were approved in the mid-2000s.
Global rollout: Over 125 countries now include HPV vaccination in national immunisation programs.
Equity issue: Uptake remains lower in many low- and middle-income countries, despite high cervical cancer burden.

Evidence

Cervical precancers: Countries with high vaccination coverage have seen dramatic declines in cervical intraepithelial neoplasia (CIN), a precursor to cancer.
Cancer prevention: Emerging real-world data shows reductions in cervical cancer rates among vaccinated cohorts.
Population impact: Herd immunity effects observed, with declines in HPV prevalence even among unvaccinated groups.
Safety monitoring: Large post-marketing studies and ongoing systems like VAERS (US), AusVaxSafety (Australia), and EudraVigilance (EU) confirm safety.

Risks / Benefits

Benefits: Strong protection against cervical cancer and other HPV-related cancers; reduction in genital warts.
Risks: Most adverse events are mild (soreness at injection site, transient fever, fatigue).
Rare events: Fainting (vasovagal syncope) after injection can occur in adolescents; no evidence of causal link to infertility, autoimmune disease, or neurological disorders.

Global Recommendations

WHO: Recommends HPV vaccination for girls aged 9–14, with either a single dose or two doses depending on local policy.
CDC (US): Routine vaccination at 11–12 years (can start at 9). Catch-up recommended through age 26.
ATAGI (Australia): Recommends a single dose for adolescents aged 12–13, with strong school-based programs achieving >80% coverage.

FAQ

Q: Who should get the HPV vaccine?
A: Adolescents of both sexes, typically between 9–14 years old. Catch-up vaccination can be offered up to age 26.

Q: Can adults benefit from HPV vaccination?
A: Yes, but benefits decrease with age as more people have already been exposed to HPV. Vaccination after 26 is generally based on individual risk factors.

Q: Does the vaccine protect against all cancers?
A: No. It protects against the majority caused by high-risk HPV strains, but cervical screening (Pap tests, HPV DNA tests) remains important.

Q: How many doses are needed?
A: WHO and many countries now recommend a single dose for adolescents, though some programs still use two doses. Adults often require three.

Disclaimer

This guide is for educational purposes only and is not a substitute for professional medical advice.
Always consult a qualified healthcare provider for diagnosis, treatment, and personal medical advice.