Study design and settings
A community-based cross-sectional study took place from June 13–23, 2023 in Wolaita Sodo town of Wolaita zone, Ethiopia. Wolaita Sodo town serves as the administrative seat of the South Ethiopia region and is known for its high population density, estimated population over 250,000 people. Administratively, the town is divided into 3 sub-cities and 25 kebeles (20).
Study population
The study population was caregivers of children ages 0 to 35 months living in Sodo town.
Inclusion criteria
Children aged 0–35 months who were living in randomly selected villages of Sodo town were included in the study.
Exclusion criteria:
Children who had no mother/caretaker in the household during the survey were excluded from the study. Moreover, in households with two or more children aged 0–35 months, the older child was excluded from the study to reduce recall biases, duplication of information and to obtain an accurate representation of the recent status of immunization services in the town.
Sample Size determination
The sample size was calculated using the single population proportion formula. Based on a previous study conducted in South Ethiopia's Demba Gofa woreda, which reported immunization coverage of 47% (21), the following single population proportion formula was employed to determine the sample size of 421 children aged 0–35 months.
Where:
n = sample size
Z = value corresponds to a 95% level of significant = 1.96
d = Margin of error = 5%
P = proportion = 47% then, = (1.96)2× (0.47) (1-0.47)/ (0.05)2
Non-response rate of (10%) making the total sample size to be 421.
Sampling procedure
Multi-stage simple random sampling was utilized in Wolaita Sodo town. The town comprised 25 kebeles and 123 villages. From these, 13 kebeles were chosen via simple random sampling (lottery method). Following this selection, a proportional allocation method was employed to randomly select 39 villages from the 13 chosen kebeles for inclusion in the study. Data collectors then generated lists of households within each village and systematically selected 10 to 11 households, resulting in a total of 421 children aged 0–35 months participating in the study. If the targeted households did not have the targeted children, data collection proceeded to subsequent households until the required number of study subjects was reached in each village.
Data collection procedures
The study engaged a team of 9 data collectors and 5 supervisors who underwent a comprehensive two-day training session to acquire the necessary skills for gathering data from the mothers or caretakers of 421 children. Data collectors were from different disciplines such as midwives, nurses, and health officers with prior experience in data collection. They had Bachelor of Science degrees from health science colleges and Universities. Supervisors, holding bachelor's degrees and above qualifications in public health were used to supervise the overall data collection process.
Structured questionnaires were used for data collection. The tool has been developed after reviewing different immunization service-related research and was pretested to ensure it captured the intended information. The questionnaires were collected house to house and administered in a face-to-face manner by trained data collectors.
Data regarding immunization services were collected from vaccination card records, which could be standard Expanded Program on Immunization (EPI) cards or any documents indicating the immunization status of children. These vaccination service registration cards were provided by vaccination service providers). Additionally, verbal reports from mothers or caretakers were obtained, including information on the timing of vaccine administration, the number of vaccines received, the site (route) of administration, and the presence of immunization scars, particularly for BCG (Bacillus Calmette-Guérin) specially for those who did not showed their child immunization cards.
Variables
Dependent variables
The dependent variable in this study was children who completed their immunization services as per national schedules.
Independent variables
Marital status, mothers’ education, mothers’ occupation, husbands’ education, occupation of the husband, age of the child, sex of the child, perceived wealth status, productive safety net program, CBHI, ANC follow-up, TD2+, place of birth, GMP, average distance, health service accessibility and PNC.
Operational definitions
Dropout: Dropout rate (DOR): The rate difference between the initial vaccines (BCG or Pentavalent I) and the final vaccines (Pentavalent III or Measles) (29).
Fully immunized
A child is considered fully vaccinated if he or she took one dose of BCG vaccine, three doses of Diphtheria Pertussis-Tetanus-Hepatitis B and Haemophilus influenza type B (DPT-HepB-Hib), three doses of the polio vaccine and one dose of IPV and measles vaccine (13).
Zero doses
A child who has not received any vaccine at all (25).
Data quality control
Before the main data collection, researchers conducted a pre-test to evaluate the effectiveness and appropriateness of the measuring instruments. Instruments have demonstrated reliability and validity through rigorous testing. Data collectors received training on the research protocols, data collection procedures, and ethical considerations. Double-entry or verification procedures are implemented during data entry to detect and correct errors. After data entry, data cleaning has been done to identify errors, inconsistencies, and outliers in the dataset. By implementing these data quality control methods, researchers enhanced the trustworthiness and credibility of research findings.
Data analysis
The collected data were exported to version 25 SPSS statistical software for analysis. The collected data underwent a cleaning process using SPSS. Descriptive statistics, including mean, median, standard deviation, percent, and frequency, were employed for analysis. Bivariate logistic analysis was conducted, considering all explanatory variables with a p-value < 0.25 for inclusion in the multivariable logistic regression analysis (22). The final multivariable analysis, at a significance level of P-value < 0.05, with Adjusted Odds Ratios (AOR) and 95% Confidence Intervals (CI), was employed to measure the degree of association between independent variables and the outcome variable (23). The study results are ultimately presented through tables and figures.
Ethical clearance
The study was approved by Wolaita zone health department Research Review Committee (Ethics Approval Number: WZH/5955/224 Dated 25/09/2015 EC). All procedures and methods performed adhere to ethical principles. Informed consent was obtained from all caretakers who voluntarily participated in the study. The participant information sheet helped them read and ask questions before consenting in writing (face to face) before the interviews.