Effectiveness of HPV Vaccine in Thai Adult Women
Effectiveness of HPV Vaccine in Thai Adult Women
-  Background: The majority of the burden of HPV-related cervical cancer is in developing
 countries while most of the effectiveness reports of HPV vaccination are currently
 coming from developed countries. Also, currently many adult women are left without
 either HPV vaccination or cervical cancer screening. Effectiveness data of currently
 available HPV vaccines among adult women in developing countries are needed for women
 and healthcare workers and policy makers to best protect women from cervical cancer.

 -  Primary Study Objective:

 - To determine the effectiveness bivalent and quadrivalent HPV vaccines in reduction of
 cervical dysplasia (Low-grade Squamous Intraepithelial Lesion or worse; LSIL+)
 attributable to HPV types 16 or 18 after at least 5 years of vaccination among Thai
 women vaccinated at their ages 20-45 years with at least one dose of the HPV vaccine

 -  Secondary Study Objectives:

 -  To measure the effectiveness of currently available bivalent and quadrivalent HPV
 vaccines in reducing the prevalence of HPV 16 or 18

 -  To measure the effectiveness of HPV vaccines in reducing any abnormal Pap smear
 result (ASC-US+)

 -  To compare the effectiveness of HPV vaccines according to the number of doses
 immunized

 -  To find out risk factor(s) for HPV 16 or 18-related cervical dysplasia in this
 cohort

 -  To assess the prevalence of other high-risk HPV types in vaccinated and
 non-vaccinated group

 -  To determine direct and/or indirect cost of HPV vaccination

 -  The hypothesis to be tested: At least one dose of vaccination with bi- or quadri-valent
 HPV vaccine will reduce the prevalence of LSIL+ attributable to HPV 16/18 by 80% after
 at least 5 years of vaccination.

 -  Materials and Methods: This study will be a retrospective matched cohort study. Data is
 to be collected either by from samples for Pap and HPV test and/or HPV 16/18 genotyping
 of the recruited participants, or from existing medical records. HPV vaccinated women at
 their ages 20-45 years (vaccinated group) and women received Pap smear at their ages
 20-45 years without vaccination (control group) will be included in the study. Pap smear
 and HPV test and/or HPV 16/18 typing result of 2 groups will be compared after ≥ 5 years
 of vaccination or baseline Pap smear. Those who don't have Pap smear results ≥ 5 years
 after vaccination or ≥ 5 years after the baseline Pap smear will be offered for a Pap
 smear and HPV 16/18 typing
Inclusion Criteria

 (vaccinated group)

 -  Thai women aged 20-45 years at the time of HPV vaccination

 -  Received at least 1 dose of bivalent or quadrivalent HPV vaccine at least 5 years ago

 -  Willing to provide written informed consent and receive Pap smear & HPV genotyping
 (only for those who need specimen collection for cervical cytology and HPV genotyping
 result)

 (control group)

 -  Thai women without history of HPV vaccination

 -  Received Pap smear result at their ages 20-45 years at least 5 years ago

 -  Willing to provide written informed consent and receive Pap smear & HPV genotyping
 (only for those who need specimen collection for cervical cytology and HPV genotyping
 result)

 Exclusion Criteria:

 -  Known pregnancy

 -  History of hysterectomy or excisional treatment of the cervix

 -  Known increased risk of bleeding

 -  Not willing to provide written informed consent