Median age at enrollment was 12.5 months (IQR: 12.0–13.1) and did not vary over the course of the study (11.8–13.3 months). Children less than 11 months of age at enrollment were excluded from further analyses (N = 41). Vaccine card retention

varied by location, ranging from 76.6% to 96.4% (p = 0.01). Children without cards (N = 296) were more likely to be girls than those with cards (N = 1832) (55% vs. 47%, p = 0.01), but were not significantly different with regard Ruxolitinib molecular weight to ethnic group or maternal education. Coverage in children with cards was high, attaining 98.9% for BCG, 95.7% for three doses of pentavalent vaccine, 95.6% for three doses of OPV and 89.7% for measles vaccine. Three-quarters of vaccinated children received their vaccines within 1 month (30 days) of the recommended age for all but the third doses of pentavalent and OPV, for

which the 75th percentile was reached 44 and 38 days late, respectively (Table 1). For all vaccines except the birth dose of OPV, coverage was three to seven percentage points higher for children with vaccine cards than for children without vaccine cards, and the differences in coverage were statistically significant (p < 0.001) C646 ( Table 2). Only OPV0 coverage was higher by maternal recall than by card (86.2% vs. 51.1%, p < 0.001). In children with vaccine cards, coverage varied by geographic location for OPV0 (27.2% in Ziani to 73% in Kilifi Township, p < 0.001), Penta3 (88.9% in Jaribuni to 100% in Banda ra Salama, p = 0.02), OPV3 (88.1% in Roka to 98.8% in Banda ra Salama, p = 0.01) and measles vaccine (76.3% in Kauma to 95% in Kilifi Township, p < 0.001); coverage was similar across locations for all other vaccines ( Fig. 1). Coverage varied by month of birth for BCG, OPV0 and OPV1, ranging from 96.6% to 100%, 35.5% to 58.8%, and 96.4% to 100% respectively, with no seasonal patterns. Coverage by sex, ethnic group, maternal education, and migrant status for each of the vaccines is shown in Table 3. With the exception of OPV0, there were limited variations in coverage across categories for each of these attributes. Pedestrian and vehicular travel

times to vaccine clinics ranged from 0 to 170 min (median: 47 min, inter-quartile range 27–73) and 0 to 132 min (median: 27 min, inter-quartile range 14–40), respectively. Log-rank tests showed differences in time-to-immunization with two not or three doses of pentavalent vaccine across pedestrian travel time strata (p = 0.02), but no clear trends with either pedestrian or vehicular travel time ( Fig. 2). Travel time was not associated with time-to-immunization with pentavalent vaccine in bivariate or multivariable proportional hazards models (HR = 1.00 for pedestrian and HR = 1.01 for vehicular travel time). In bivariate models, children in the most educated areas had higher immunization rates than those in less educated areas (HR[group 4 vs. groups 1–3] = 1.22, 95% CI 1.17–1.28) and migrant children had slightly higher rates than non-migrants (HR = 1.