Quadrivalent HPV vaccine initiationa among girls aged 9–17 years, by age National Health Interview Survey, United States, 2008
a Initiation refers to receipt of 1 dose of the vaccine.
bEstimate for girls aged 9–10 years are unstable and should be interpreted with caution.
Percentages are weighted to the population of girls aged 9–17 years.
Missing data (total <1%) and refused or don’t know (total = 2.2%) are included in percentage calculations.
Error bars are 95% CI around the estimated percentage.