Table 3.

Factors associated with human papillomavirus (HPV) vaccine series initiation among adolescents aged 13-17, Montana, National Immunization Survey–Teen, 2017^a

Factor	Sample no.	Weighted % (95% CI)	PR (95% CI) for HPV vaccine series initiation
			Unadjusted	Adjustedb
Adolescent received a Tdap vaccine after 11th birthday
Yes	292	90.4 (86.5-94.3)	3.8 (1.8-8.0)	3.3 (1.4-8.1)
No	34	9.6 (5.7-13.5)	Reference	Reference
Parent/guardian received a medical provider’s recommendation to vaccinate adolescent against HPVc
Yes	245	78.9 (73.3-84.6)	2.4 (1.6-3.8)	2.3 (1.5-3.6)
No	63	21.1 (15.4-26.7)	Reference	Reference

Abbreviations: PR, prevalence ratio; Tdap, tetanus-diphtheria-acellular pertussis.

^aData source: Centers for Disease Control and Prevention.¹⁹

^bAdjusted for adolescent’s age, sex, maternal education level, health insurance type, annual family household income, race/ethnicity, whether the child had a checkup in the previous 2 years, and the other factor listed in the table.

^cThirteen people answered that they did not know whether they had received a medical provider recommendation to vaccinate, and data were missing for 5 people; these 18 people were excluded from analysis.