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Table 4 Factors associated with childhood immunization research productivity identified by zero-truncated negative binomial regression models.

From: A bibliometric analysis of childhood immunization research productivity in Africa since the onset of the Expanded Program on Immunization in 1974

  Univariable Multivariable
Variable IRR (95% CI) P-value IRR (95% CI) P-value
DTP3 coverage 0.38 (0.04, 3.42) 0.389 not included  
Gross domestic product (US dollar) 1.46 (1.23, 1.73) 0.000 1.55 (0.82, 2.93) 0.177
Adult literacy rate 1.21 (0.36, 4.09) 0.764 not included  
Physicians per 100,000 population 1.27 (0.92, 1.74) 0.147 0.77 (0.56, 1.04) 0.089
Total expenditure on health 3.98 (0.97, 16.21) 0.054 0.68 (0.12, 3.94) 0.665
Private expenditure on health 3.18 (1.62, 6.22) 0.001 3.64 (1.46, 9.07) 0.006
Research and development expenditure 1.47 (1.21, 1.78) 0.000 0.96 (0.49, 1.87) 0.897
Human development index 2.65 (0.45, 15.57) 0.280 not included  
  1. DTP3, third dose of the diphtheria-tetanus-pertussis vaccine by one year of age; IRR, incidence rate ratio; CI, confidence intervals