Granularity matters – measles first- and second-dose vaccination coverage in Poland, 2014–2018

Introduction and Objective.Vaccination coverage of 95% is essential to interrupt measles transmission.Accurate measurement of vaccine uptake is critical for identifying vulnerable populations and guiding public health interventions.The aim of the study is to: present differences in the sufficient measles vaccination (MCV) coverage in Poland, measured at different granularity level, and to identify clusters with sufficient/insufficient MCV coverage.Materials and Method.Data on MCV coverage was extracted from annual reports collected by sanitary-epidemiological stations in Poland between 2014-2018.Spatial analysis using Local Moran's I was performed to identify neighbouring poviats with similar MCV rates and outlier areas with markedly dissimilar values.Results.MCV coverage in Poland exhibited substantial spatial and temporal variability.The first dose of measles vaccination (MCV1) coverage ranged from 89% -99% at the voivodeship level and from 80% to 100% at the poviat level, while the second dose measles vaccination (MCV2) coverage ranged from 84% -99% and from 32.3% -100%, respectively.Spatial disparities were particularly pronounced in several voivodeships, with Mazowieckie consistently demonstrating both the highest positive and negative deviations between poviat-level and voivodeship-level coverage.Statistically significant local spatial autocorrelation was observed in an increasing number of poviats for MCV1, rising from 14 in 2014 to 47 in 2018.For MCV2, the number of poviats with significant clustering fluctuated, peaking at 27 in 2015.Conclusions.The use of fine-grained poviat-level data revealed disparities in MCV coverage and localized gaps that would be obscured at the voivodeship level, underscoring the importance of high-resolution spatial analysis for guiding targeted vaccination efforts and improving public health equity.