Maya B. Mathur Castilleja School, Palo Alto, CA Predictors of HPV Vaccination and Participation in Vaccination Decision-Making among High School Girls Thank you Good afternoon Maya Mathur, senior at Castilleja School in Palo Alto Two years ago, doctor recommended the HPV vaccine Parents agreed. I knew little about HPV and the vaccine, but went along. New Scientist article describing the controversy catalyzed by the vaccine. Since Gardasil’s approval by the Food and Drug Administration in 2006, some vocal parents, doctors, and lawmakers have supported immediately requiring all girls as young as 11 or 12 years old to receive the vaccine, while others have expressed concern for potential unknown side effects, infringement upon personal choice, or implicit approval of teenage sexual activity. Maya B. Mathur Castilleja School, Palo Alto, CA CDC 43rd National Immunization Conference, March 30 – April 2, 2009, Dallas, TX

Introduction The public policy controversy over mandating the human papillomavirus (HPV) vaccine Gardasil has primarily involved opinions of politicians, healthcare professionals, and parents. However, attitudes and knowledge of girls themselves have not been examined.

Study Objectives To determine: #1: to what extent high school girls are participating in vaccine decision-making. #2: what sources of vaccine information high school girls use in their vaccine decision-making. #3: the knowledge of high school girls about HPV and HPV vaccine-related knowledge #4: the attitudes of high school girls towards mandatory vaccination.

Methods – 1 Design: Cross-sectional study Target Population: Girls in grades 9 – 12 in the U.S. Study Population: Girls in grades 9 – 12 from: all-girls, private, non-sectarian school (Main Study) co-educational public high school (Pilot Expansion Study) (Both schools located in the San Francisco Bay Area) Variables Socio-demographic factors, attitudes, vaccine-related knowledge Vaccination, participation in vaccination decision

Methods - 2 Sampling: Random, stratified by grade (Main Study) Convenience sample (Pilot Expansion Study) Survey Administration 59 multiple-choice and several write-in questions Main Study: Anonymous online survey (N = 100) Pilot Expansion Study: Paper surveys distributed by teachers for completion in science classes (N = 75)

Methods 3: Survey Development Possible Source of Bias/Confounding Action Leading questions Extreme care to develop balanced presentation Use of feedback from pilot group Gaining vaccine-related knowledge during survey Use of decoy questions about other STDs and ovarian cancer Priming events affecting attitudes and behavior Questions that may result in “stereotype threat” (e.g., religion, parental education, school attended, frequency of doctor visits, etc.) appeared after questions about attitudes and knowledge

Summary of Survey Responses Main Study Pilot Expansion Study 75 distributed 100 distributed 95 returned 5 not returned 74 returned 1 not returned Figure 1: Summary of Survey Responses. 81 completed 14 not completed 74 completed

Factors Associated with Vaccination

Percentage Vaccinated by Grade Level

Associations with Vaccination Not associated with vaccination (p > 0.10) Parental education Post-HS plans Estimate of HPV, warts, cervical cancer frequency Frequency of doctor visits Public co-ed school vs. private all-girls school Associated with vaccination (p < 0.10) Older age Grade 11/12 (vs. 9/10)† Attending religious services† Info from MD or nurse Higher knowledge score† †p < 0.05, vaccinated vs. unvaccinated main study

Vaccine Decision-Making

Participated in Vaccine Decision-Making

From What Source(s) Have you Heard About Gardasil? (Main Study + Pilot Expansion Study)

Importance of Various Sources of Information in Decision-Making by Girls % citing as important N = 25 girls who participated in vaccine decision-making (main study)

Vaccine-Related Knowledge

Vaccine-Related Knowledge 12 multiple-choice factual questions Total vaccine-related knowledge score: 0-12 3 write-in questions estimating risk % of sexually-active people in US who have had an infection with HPV % of sexually-active people in the US who have genital warts % of women in the US get cervical cancer at some point in their lives

Vaccine-Related Knowledge Score (Main Study + Pilot Expansion Study) % correct: 69.1% 43.7%

Can viruses cause cancer? 30-40% incorrect (N = 66) (N = 130)

Can men get infections with HPV? 50-60% incorrect (N = 66) (N = 130)

Can you get STDs after vaccination? 25-30% of unvaccinated girls got it wrong (N = 66) (N = 130)

What does Gardasil do for infection with HPV? 25-35% incorrect among unvaccinated girls <100% of vaccinated girls knew this (N = 66) (N = 130)

What does Gardasil do for genital warts? 70% incorrect (N = 66) (N = 130)

What does Gardasil do for cervical cancer? 15-30% incorrect among unvaccinated <100% correct among vaccinated (N = 66) (N = 130)

Estimates of Risk

Estimation of Risk of HPV and HPV-Related Conditions

Attitudes Towards Mandatory Vaccination

Agreement with Mandatory Vaccination *** *** *** ***p < 0.001 Chi-Square agree/disagree/neutral

Conclusions and Implications Implication(s) or Actions H.S. girls frequently participate in HPV vaccine decision-making: 9/10th: 24% 95% CI [9%, 40%] 11/12th: 49% 95% CI [33%, 65%] Good education of adolescent girls needed to ensure well-informed decisions Girls’ knowledge of own behavior could be used to better risk-stratify Target vaccine to those most at risk (health resource limitations)? There are significant vaccine-related knowledge gaps Target education based on known knowledge gaps (possible need for booster, STD still possible, etc.) Girls rate parents, doctors, and own reading to be most important sources of information. Disseminate information via sources girls rate as v. important to them

Limitations Cross-sectional design Associations, not causality Without longitudinal evaluation, time sequence of attitudes and knowledge relative to vaccination cannot be known Non-response bias Generalizability Pilot expansion study suggests generalization to wider population of high school girls than in the main study However, future studies should aim to recruit subjects from a wider geographic range, more representative of the U.S. population

Thank you!