Prevalence, geographical distribution and factors associated with pentavalent vaccine zero dose status among children in Sindh, Pakistan: analysis of data from the 2017 and 2018 birth cohorts enrolled in the provincial electronic immunisation registry.

OBJECTIVES

To estimate the prevalence of zero dose children (who have not received any dose of pentavalent (diphtheria, tetanus, pertussis, type B and hepatitis B) vaccine by their first birthday) among those who interacted with the immunisation system in Sindh, Pakistan along with their sociodemographic characteristics and risk factors.

DESIGN AND PARTICIPANTS

We conducted a descriptive analysis of child-level longitudinal immunisation records of 1 467 975 0-23 months children from the Sindh's Zindagi Mehfooz (Safe Life) Electronic Immunisation Registry (ZM-EIR), for the birth cohorts of 2017 and 2018.

SETTING

Sindh province, Pakistan which has a population of 47.9 million people and an annual birth cohort of 1.7 million.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome measure was zero dose status among enrolled children. Logistic regression was performed to identify the risk factors associated with the zero dose status.

RESULTS

Out of 1 467 975 children enrolled in the ZM-EIR in Sindh, 10.6% (154 881/1 467 975) were zero dose. There were sharp inequities across the 27 districts. Zero dose children had a lower proportion of hospital births (28.5% vs 34.0%; difference 5.5 percentage points (pp) (95% CI 5.26 to 5.74); p<0.001) and higher prevalence from slums (49.5% vs 42.3%; difference 7.2 pp (95% CI 6.93 to 7.46); p<0.001), compared with non-zero dose children. Children residing in urban compared with rural areas were at a higher risk (relative risk (RR): 1.20; p<0.001; 95% CI 1.18 to 1.22), while children with educated compared with uneducated mothers were at a lower risk of being zero dose (RR: 0.47-0.96; p<0.001; 95% CI 0.45 to 0.98).

CONCLUSIONS

Despite interacting with the immunisation system, 1 out of 10 children enrolled in the ZM-EIR in Sindh were zero dose. It is crucial to monitor the prevalence of zero dose children and investigate their characteristics and risk factors to effectively reach and follow-up with them.