Tiered Clinician Vaccine Communication Strategy to Improve Childhood Vaccine Uptake: A Cluster Randomized Clinical Trial.

Importance: No experimental studies to date have tested the effectiveness of clinician communication strategies to improve vaccine uptake among children of parents with negative vaccine attitudes. Objective: To evaluate the effect of a tiered vaccine communication strategy on children of parents with negative vaccine attitudes. Design, Setting, and Participants: This cluster randomized clinical trial was conducted from September 1, 2019, to March 31, 2023, at primary care pediatric clinics in Colorado (n = 12) and Washington State (n = 12). Parents with negative vaccine attitudes who had infants 2 months or younger and were receiving health supervision at a participating clinic during the intervention period were eligible for the study. Intervention: Tiered strategy in which clinicians initiated vaccine discussions with all parents using a presumptive format and then used motivational interviewing with parents who verbally resisted recommended vaccines. Clinicians at intervention clinics received training on the tiered vaccination strategy, whereas clinicians at control clinics practiced usual care. Main Outcomes and Measures: Child vaccination status at 19 months of age characterized as percentage of days underimmunized (DU) in receiving recommended doses of 8 routinely recommended vaccines, with 0% DU described as up to date (UTD) on time. Results: A total of 937 parent-child dyads (intervention: n = 586; control: n = 351) were included in analysis; 434 (46.3%) had an annual household income greater than $75 000 and 682 (72.8%) had some college, a 2-year degree, or more education. In bivariable analyses, more intervention (vs control) participants were UTD on time (130 [22.2%] vs 64 [18.2%]), but intervention (vs control) participants had higher mean (SD) percentage of DU (32.1% [37.9%] vs 23.7% [32.4%]). Variation was observed across states, with intervention participants in Washington (vs Colorado) having a lower mean (SD) percentage of DU (22.4% [31.8%] vs 39.6% [40.1%]) and more infants who were UTD on time (77 [30.0%] vs 53 [16.1%]). In multivariable regression models, there was no difference between intervention and control arms in mean (SD) percentage of DU (adjusted incidence rate ratio, 1.06; 95% CI, 0.69-1.63) or UTD on time (adjusted odds ratio, 1.45; 95% CI, 0.69-3.04), although there were increased odds of being UTD on time among Washington intervention (vs control) participants (adjusted odds ratio, 2.47; 95% CI, 1.09-5.59). Conclusions and Relevance: In this cluster randomized clinical trial of a tiered vaccine communication strategy, vaccine uptake of children of parents with negative vaccine attitudes did not improve, although state-specific effects were observed. Trial Registration: ClinicalTrials.gov ID: NCT03885232.