Jason M. Glanz, Nicole M. Wagner, Komal J. Narwaney, Courtney R. Kraus, Jo Ann Shoup, Stanley Xu, Sean T. O’Leary, Saad B. Omer, Kathy S. Gleason, Matthew F. Daley

Interventions to address vaccine hesitancy and increase vaccine acceptance are needed. This study sought to determine if a Web-based, social media intervention increases early childhood immunization. A 3-arm, randomized controlled trial was conducted in Colorado from September 2013 to July 2016. Participants were pregnant women, randomly assigned (3:2:1) to a Web site with vaccine information and interactive social media components (VSM), a Web site with vaccine information (VI), or usual care (UC). Vaccination was assessed in infants of participants from birth to age 200 days. The primary outcome was days undervaccinated, measured as a continuous and dichotomous variable. Infants of 888 participants were managed for 200 days. By using a nonparametric rank-based analysis, mean ranks for days undervaccinated were significantly lower in the VSM arm versus UC (P = .02) but not statistically different between the VI and UC (P = .08) or between VSM and VI arms (P = .63). The proportions of infants up-to-date at age 200 days were 92.5, 91.3, and 86.6 in the VSM, VI, and UC arms, respectively. Infants in the VSM arm were more likely to be up-to-date than infants in the UC arm (odds ratio [OR] = 1.92; 95% confidence interval [CI], 1.07-3.47). Up-to-date status was not statistically different between VI and UC arms (OR = 1.62; 95% CI, 0.87-3.00) or between the VSM and VI arms (OR = 1.19, 95% CI, 0.70-2.03). Providing Web-based vaccine information with social media applications during pregnancy can positively influence parental vaccine behaviors.