In children, the global burden of vaccines-preventable diseases (VPDs) and deaths can be averted by adopting timely immunization practices. Administering immunization to a child within 28 or 30 days of the designated immunization date is referred to as timely immunization. Besides timely immunization, immunization non-compliance (invalid or delayed or missed immunization) increases the risk of various forms of VPDs and death in children, particularly living in urban slums. This study was designed to examine the immunization practices and to measure the determinants of immunization non-compliance in children living in urban slums of Karachi, Pakistan. A community-based retrospective cohort was carried out from October-2018- to August-2019 in six different urban slums of Karachi. Immunization status of children aged less than 2 years was assessed by reviewing their vaccination card. Children from each slum were approached via 30x7 multistage stratified cluster sampling technique. Data of each child was analyzed descriptively and inferentially using statistical software, i.e., Jamovi version 1.2.25. The practice of timely immunization was observed in approximately half of children, i.e., 49.8% (n=457). The immunization rate at birth (first-visit) was 100%, of which 95.7% were timely immunized. Following the second immunization visit, a sharp decline in the immunization rate, including timely immunization rate was observed. Lack of knowledge, childhood illnesses, lack of interest, and vaccines unavailability were the main reasons of immunization non-compliance. However, an increase in paternal education was significantly associated with decreasing the odds of immunization non-compliance. A decrease in the practice of timely immunization is replaced by either invalid and/or delayed and/or missed immunization practices. Thus, timely immunization is crucial for preventing infectious diseases and promoting the health of a child.

Missed, Invalid, Delayed, Immunization, Children, Karachi