Study and setting
Techiman Municipal is situated in the central part of the Brong-Ahafo Region of Ghana. It shares boundaries with five districts, namely: Techiman North, Akumadan, Nkronza, Wenchi and Sunyani West Districts. The Municipality has a population of 166,497 projected from the 2010 population and housing census [11]. This population represents about 6.4% of the Regional total population. It has the highest population density of 256.5 people per square kilometer. Health services are provided through public and private health facilities. They include Health centres, Community-based Health Planning and Services Compounds (CHPS), Clinics and Maternity homes. As part of decentralization of the health system, the Municipality has been demarcated into seven sub-municipals to facilitate health services delivery.
Study design
A cross-sectional cluster survey design was employed. All children between the ages of 12–23 months were eligible. Firstly, 30 clusters (communities) were selected in the Municipality. They were selected using probability proportional to their size (estimated population data). The community data was provided by the Municipal health directorate. The second stage involved the use of the EPI random walk method to select 20 children from each cluster. Two field enumerators were recruited and trained on the study protocol and semi-structured questionnaires. In addition, a pre-test was conducted after the training to determine the validity and reliability of the study tools. Actual data collection happened from 30th January to 20th February 2016.
Sampling procedure
A '30 × 20' cluster sampling method was used for the study. The 30 clusters were selected using cluster identification form through the probability proportionate to size simple random method. Twenty (20) households from each of the 30 clusters were sampled. The starting point was selected as the first household for each cluster and then continued to the next nearest household until 20 eligible children were obtained. Door-to-door visits and face-to-face interviews were conducted with mothers/caregivers who had children 12–23 month as well as observation of the children for the presence of BCG scar.
Sample size determination
The sample size was calculated using the formula N = [De × Z2 × p (1-p)]/d2 [14]. Where, N is the sample size, De (2) is the design effect, the ratio between the variance from the cluster design to the variance that would be obtained from a simple random sampling [14], Z (1.96) is the certainty wanted expressed in the percentage point of normal distribution corresponding to the 2-sided level of significant, P (77%) is the immunization coverage of Ghana [10] and d (5%) is the desired width of the confidence interval. Therefore; N = [2 × (1.96)2 × 0.77× 0.23]/ (0.05)2 = 545. A non response rate of 10% was added, giving a total sample of 600. Proceeding from house to house looking for the inclusion criteria of haven at least one child aged 12–23 months, 600 respondents (mothers and caregivers) were selected and interviewed.
Data collection instrument and procedures
A modified WHO-EPI semi-structured questionnaire was used for the data collection. The questionnaire included items on socio-demographic characteristics and infant immunization information. After informed consent was received, the mothers/caregivers of selected children participated in a structured interview. Information on immunization coverage was obtained in two ways: immunization cards and mothers’/caregivers’ verbal reports. All mothers/caregivers were asked to show the interviewer the child health record card with immunization dates. If the card was available, the interviewer then extracted the dates of each immunization received. In cases where it indicated in the immunization card that the child did not receive all vaccines, the mother/caregiver was asked whether the child had received other vaccines that were not recorded on the card. If they answered yes, the information was recorded. If there was no card, or if the mother/caregiver was unable to show it to the interviewer, the child’s immunization information was based on their recall. Secondary data on routine immunization coverage was also extracted from registers and annual reports at the TMHD.
Operational definitions
Fully immunized
Child received 1 dose of Bacillus Calmette-Guerin (BCG), 4 doses of Oral Polio Vaccine (OPV), 3 doses of Pentavalent, 3 doses of Pneumococcal Vaccine (PCV), 2 doses of Rotarix (Rota) and 1 dose of Measles and 1 dose of Yellow fever vaccines is said to be fully immunized. That is, a total of seven (7) vaccines and fifteen (15) doses.
Partially immunized
Child missed some of the prescribed vaccines doses considered to protect against vaccine preventable diseases.
Not immunized
Child received none of the prescribed vaccines doses considered to protect against vaccine preventable diseases.
Dropout rate
Percentage difference in coverage between two different doses in sequence.
Data processing and analysis
At the end of the interviews, questionnaires were checked for completeness and internal consistency. Data was entered, cleaned and analyzed using Statistical Package for Social Sciences (SPSS) version 17.0. Descriptive statistics such as frequencies and percentages were produced and presented in tabular form. In addition binary regressions was also performed between dropout rate and socio-demographic characteristics of the respondent. Moreover, dropout rates between two vaccines doses in sequence were computed using the formula: Dropout rate = [(coverage of initial vaccine dose – coverage of ending vaccine dose) ÷ (coverage of initial vaccine dose) × 100], e.g. (BCG-Measles)/ (BCG)*100.
Ethics approval and informed consent
An introductory letter and approval was received to conduct the study from the School of Allied Health Sciences, University for Development Studies, Tamale, Ghana. In addition, permission letter was obtained upon a written request and explanation of the study protocol, methods and questionnaire from the Techiman Municipal Health Directorate. At the individual level, the protocol, methods and approach was explained in English or Twi (main local language) and a written consent was obtained from each respondents of 18 years of age and above before the interview was conducted. Among the few teenagers, consent was obtained through their husbands (those married) or parents (those unmarried). Respondents were informed that participating was voluntary and it was their right to stop at any time. They were also informed of data confidentiality by not using any personal identifiers.