Medical Records   Received Vaccine No Vaccine Correct Recallb (%) P Value Gender-Specific Reporting       < 0.195c Female Self-Report (n = 136)     69.1   Received Vaccine 74 9     No Vaccine 6 20     Unsure 19 8     Male Self-Report (n = 81)     60.5   Received Vaccine 22 5     No Vaccine 3 27     Unsure 5 19     Age-Specific Reporting       < 0.002d 12-14 (n = 29)     48.3   Received Vaccine 8 2     No Vaccine 1 6     Unsure 6 6     15-17 (n = 92)     64.1   Received Vaccine 37 3     No Vaccine 6 22     Unsure 12 12     18-19 (n = 56)     60.7   Received Vaccine 25 7     No Vaccine 2 9     Unsure 6 7     20-23 (n = 40)     90   Received Vaccine 26 2     No Vaccine 0 10     Unsure 0 2     All Participants Self Report (n = 217)     65.9   Received Vaccine 96 14     No Vaccine 9 47     Unsure 24 27

Table 2: Initiation of HPV Vaccination Series: Agreement of Genderand Age-Specific Self-Report to Medical Records (n=217). Notes: Initiation=one or more doses; Of all participants self-report: sensitivity 74.4 (i.e. 96/(96+9+24)), specificity 53.4 (i.e. 47/(47+14+27)), positive predictive value 70.1 (i.e. 96/(96+14+27)), negative predictive value 58.8 (i.e. 47/(47+9+24)). Correct Recall=proportion of participants who accurately identify vaccination status (either receiving zero vaccinations, or receiving at least one vaccination) based on medical records; those who are "unsure" are incorrect. OR Female (vs. Male) 1.46, 95% CI .82-2.60. OR 20-23 to <20: 2.34, 95% CI 1.06-5.17