Abnormal Pap tests after the HPV vaccine

Area of Science:

• Oncology
• Virology
• Public Health

Background:

• Cervical cancer affects 500,000 women globally, causing 275,000 deaths annually.
• Persistent infection with oncogenic human papillomavirus (HPV) types causes cervical cancers.
• The Pap test detects squamous cell carcinoma precursors; Australia introduced a free quadrivalent HPV vaccine in 2007 for females aged 12-26.

Purpose of the Study:

• To explain why vaccinated young women may still present with Pap test abnormalities.
• To address expectations regarding the impact of HPV vaccination on cervical cancer and Pap test results.

Main Methods:

• This is a review/discussion article, not a primary research study.
• Analysis of HPV vaccine efficacy and its implications in the context of pre-vaccination exposure and vaccine type coverage.

Main Results:

• HPV vaccines demonstrate nearly 100% prophylactic efficacy against targeted HPV types.
• Vaccine efficacy relies on the recipient not being previously infected with the specific HPV type.
• Most women aged 18-26 vaccinated likely had prior exposure to one or more HPV types.

Conclusions:

• A substantial number of vaccinated young women will continue to show Pap test abnormalities.
• Abnormalities are attributed to HPV exposure before vaccination and HPV types not covered by the vaccine.
• A significant reduction in cervical cancer and Pap test abnormalities will take several years to become apparent.