Individual and Neighborhood Factors Associated with Failure to Vaccinate against Influenza during Pregnancy.

Zerbo, Ousseny; Ray, Thomas; Zhang, Lea; Goddard, Kristin; Fireman, Bruce; Adams, Alyce; Omer, Saad; Kulldorff, Martin; Klein, Nicola P

Influenza vaccine uptake among pregnant women remains low. We investigated whether unvaccinated pregnant women cluster geographically and determined factors associated with failure to vaccinate using a spatial and multivariate logistic regression analyses. Pregnant women in 2015 or 2016 member of Kaiser Permanente Northern California were included in the study. More than half (53%) of the 77,607 included pregnant women were unvaccinated. Spatial analysis identified 5 clusters with high prevalence of unvaccinated pregnant women. The proportion of unvaccinated ranged from 57% to 75% within clusters compared to 51% outside clusters. In covariate-adjusted analyses,, residence in a cluster was associated with a 41% increase in the odds of being unvaccinated (OR = 1.41, 95% confidence interval (CI): 1.36,1.46). The odds of being unvaccinated increased for black (OR = 1.58, CI: 1.49, 1.69), Hispanic (OR = 1.15, CI: 1.05, 1.25), subsidized insurance (OR = 1.18, CI: 1.11, 1.24), women with < 5 prenatal visits (OR = 1.85, CI: 1.60, 2.16) and neighborhoods with high deprivation index (OR = 1.14, CI: 1.07, 1.21). In conclusion, unvaccinated pregnant women clustered geographically and by key sociodemographic factors. These findings suggest that interventions to increase influenza vaccine coverage among pregnant women are needed, particularly in vulnerable populations.