Table 3. Factors associated with measles vaccination coverage.
| Indicators (units) | Negative binomial regression modela | |||
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| Univariable model | Multivariable modelb | |||
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| IRR (95% CI) | P-value | IRR (95% CI) | P-value | |
| Population densityc | 1.009 (1.007–1.011) | <0.001 | 1.004 (1.001–1.006) | 0.011 |
| Proportion of foreign nationals (%) | 1.006 (1.004–1.008) | <0.001 | 1.002 (1.000–1.005) | 0.033 |
| Proportion of single-father households (%) | 0.946 (0.931–0.961) | <0.001 | 0.976 (0.954–0.999) | 0.042 |
| Proportion of single-mother households (%) | 0.994 (0.992–0.996) | <0.001 | 1.002 (0.999–1.006) | 0.228 |
| Area deprivation indexd | 0.972 (0.967–0.977) | <0.001 | 0.970 (0.960–0.980) | <0.001 |
| Proportion of mothers aged ≥30 years (%) | 1.001 (1.000–1.001) | <0.001 | 0.999 (0.998–0.999) | <0.001 |
| Number of medical facilities per habitable land area (number per 1 km2) | 1.002 (1.001–1.002) | <0.001 | 1.000 (0.999–1.001) | 0.954 |
| Number of pediatricians (number per 1,000 population) | 1.061 (1.028–1.094) | <0.001 | 1.003 (0.955–1.053) | 0.911 |
| Number of non-pediatric medical doctors (number per 1,000 population) | 1.003 (1.001–1.004) | <0.001 | 1.000 (0.998–1.003) | 0.850 |
CI, confidence interval; IRR, incidence rate ratio.
aThe dependent variable was the number of children aged 1 year who received the measles vaccine in 2022. The offset term was the number of children eligible for the first dose of measles vaccine as of October 1, 2022.
bThe independent variables were all variables in the Table.
cPopulation density, defined as the number of people per square kilometer of land area (number/km2), was subjected a logarithmic transformation using the natural logarithm due to its right-skewed distribution. This indicator is unitless. Each one-unit increase in the logarithm of population density corresponds to a population density (number/km2) increase of approximately 2.72 times.
dThe area deprivation index, derived from the 2020 census results, was used as an indicator of socioeconomic status at the municipal level. This composite indicator comprises the weighted sums of poverty-related census variables. This indicator is unitless.