Trends in childhood vaccination in Pakistan and associated factors; 2006-2018

Introduction: Pakistan still has ongoing transmission of wild type polio virus. This study aims to determine changes in full vaccination with recommended Expanded Program on Immunization vaccines, including polio, by several socio-economic and demographic factors. Methods: We used three waves of Pakistan's Demographic and Health Survey, a population-based cross-sectional study from 2006-07 (N = 1471), 2012-13 (N = 1706), and 2017-18 (N = 1549), analyzed by residence, wealth, and sociodemographic factors. Analysis was limited to children aged 12-23 months in Punjab, Sindh, Northwest Frontier Province/Khyber Pakhtunkhwa and Balochistan. Full vaccination was measured as receipt of one Bacillus Calmette-Gu & eacute;rin dose, one measles dose, 3 polio doses, and 3 Diphtheria-Tetanus-Pertussis doses. Odds ratios (ORs) and 95 % confidence intervals (CIs) from logistic regression were used to determine associations between undervaccination and demographic variables. Results: Full vaccination coverage was 50.6 % in 2006-07, 54.7 % in 2012-13, and 68.3 % in 2017-18. In 2006-07, the odds of undervaccination were significantly higher in Sindh (OR: 1.74, 95 % CI: 1.30, 2.31) than Punjab, and disparities across province changed over time (P < 0.0001); notably, undervaccination was significantly higher in Sindh, KPK, and Balochistan than Punjab in 2017. Compared to the middle wealth quintile, the poorest had significantly higher odds of undervaccination in 2006-07 (OR: 2.58, 95 % CI: 1.76, 3.78), and this did not significantly change over time (P = 0.2168). The proportion of those with a polio birth dose increased across waves from 56.3 % in 2006-07 to 83.7 % in 2017-18; receiving three or more polio vaccine doses remained unchanged. Conclusion: This study showed that the proportion of fully vaccinated children in Pakistan increased across three waves. Full vaccination and administration of polio vaccine birth doses have increased recently in Pakistan. The association between undervaccination with province differed significantly across the waves, with vaccination disparities between provinces increasing. Those in the poorest wealth quintile had the greatest odds of undervaccination.