Affordable Care Act state Medicaid expansion and human papillomavirus vaccination among adolescent and young adult US women: A national study.

Objective: To ascertain the impact of Affordable Care Act (ACA) state Medicaid expansion on human papillomavirus (HPV) vaccination among both adolescent and young adult US women.

Data Sources: We used state-level data on ACA Medicaid expansion and individual-level data on US women aged 15-25 years living at or below 138% of the Federal Poverty Level (FPL) from the 2011-2017 waves of the National Survey of Family Growth (N = 2408).

Study Design: We conducted a quasi-experimental study examining the association between ACA state Medicaid expansion and HPV vaccination initiation among eligible adolescent and young adult US women.

Methods: We used linear probability modeling within a difference-in-differences approach, adjusting for individual- and state-level covariates.

Principal Findings: Adjusting for individual- and state-level covariates, we found a negative association between Medicaid expansion and HPV vaccination among US women aged 15-25 years living in low-income households in the first year post-expansion (coefficient: -15.9 percentage points; 95% confidence interval [CI]: -30.1, -1.6 points). In contrast, we observed a positive association in the third year post-expansion (coefficient: 20.5 percentage points; 95% confidence interval [CI]: -1.8, 42.9 points).

Conclusions: Medicaid expansion may have increased HPV vaccination among adolescent and young adult US women over time. Additional research is needed to identify the mechanisms and differential effects of Medicaid expansion on HPV vaccination among diverse subgroups of US women.