Vaccination Coverage and Associated Factors among Children Aged 12–23 Months in Debre Markos Town, Amhara Regional State, Ethiopia

Introduction. Vaccination is the administration of a vaccine or a biological substance intended to stimulate a recipient’s immune system to produce antibodies or undergo other changes that provide future protection against specific infectious diseases.Objective. To determine vaccination coverage and associated factors among children aged 12–23 months in Debre Markos town 2016. Methods. Community-based cross-sectional studywas employed among 288mothers/caretakers to child (12–23months) pair. Study populations were selected using systematic random sampling technique. Structured interviewer administered questionnaires were used to collect data. Variables withP value of less than 0.05 inmultivariate analysis were considered as statistically significant at 95% CI.Result. About 264 (91.7%) of children were completely vaccinated.Male birth 3.24 (1.16–9.04), wanted pregnancy 2.89 (1.17–7.17), having at least twoANC follow-ups 4.04 (1.35–12.06), and short distance fromvaccination site 3.38 (1.29–8.86) were found positively associated with complete immunization. Conclusion and Recommendation. There was relatively high immunization coverage in the study. Child’s sex, ANC follow-up, type of pregnancy, and distance from health institution were factors associated with complete vaccination. Preventing unwanted pregnancy and promoting ANC and postnatal follow-up should be strengthened. Vaccination sites should also be further expanded.


Introduction
Vaccination is the administration of a vaccine, that is, a biological substance intended to stimulate a recipient's immune system to produce antibodies or undergo other changes that provide future protection against specific infectious diseases. Immunization is the stimulation of changes in the immune system through which that protection occurs [1].
The Expanded Program on Immunization (EPI) was established by the World Health Organization in 1974 to control vaccine preventable diseases. In Ethiopian, EPI program was launched in 1980 [2]. It was launched with the aim of reducing mortality and morbidity of children and mothers from vaccine preventable diseases. The target group when the program started were children under two years of age until it changed to under one year in 1986 to be in line with the global immunization target [3].
In a study conducted in Ethiopia, it was found that 73.2% of the children were fully immunized, 20.3% were partially immunized, and 6.5% received no vaccine [4]. In another study conducted, 76% of the children were fully immunized. Dropout rate was 6.5% for BCG to measles, 2.7% for Penta 1 to Penta 3, and 4.5% for Pneumonia 1 to Pneumonia 3 [5].
Vaccination is a highly effective method of preventing certain infectious diseases. Routine immunization programs protect most of the world's children from a number of infectious diseases that previously claimed millions of lives each year [6].
In Ethiopia, vaccine preventable diseases contribute substantially to under-five mortality as well as morbidity. Diarrhea (18%), pneumonia (18%), measles (1%), and meningitis are the leading causes of child mortality in the country [3].
Ten currently available EPI vaccines in Ethiopia include (BCG, measles, DPT-HepB-Hib or pentavalent, rotavirus, 2 Advances in Public Health pneumococcus vaccine (PCV), and OPV. Moreover, it is directed in the implementation guideline to introduce Inactivated Polio Virus (IPV), measles-rubella, meningitis, and yellow fever vaccines for less than one-year-old children [2].
However, many factors are linked to un/undervaccinated children. In Ethiopia, living in rural area and distance to health clinic, mothers with limited education, and socioeconomic capital are linked to low vaccine uptake and placing children at risk for vaccine preventable diseases [7]. Mother education, mothers' perception to accessibility of vaccines, mothers' knowledge to vaccine schedule of their site, place of delivery, and living altitude were independent predictors of children immunization status [4].
As a result of the ten vaccines introduced, complementary with other interventions, many deaths due to vaccine preventable disease are being averted than ever before [3]. However, still related system-wide barriers are linked to incomplete vaccination or unvaccination of children.
As a result, childhood immunization and associated factors should be targeted through educational research. This study was conducted to identify the current gaps and supplement the past studies. Thus, this study can be used as a reference for health care providers, health care educators, policy makers, and future researchers in this and/or related fields.

Objectives
The main objective is to determine vaccination coverage and associated factors among children aged 12-23 months in Debre Markos town, Amhara Regional State, Ethiopia, 2016.

Study Area.
The study was conducted in Debre Markos town. Debre Markos is found in East Gojjam Zone of Amhara Regional State of Ethiopia.

Study Period.
The study was conducted from August to September, 2016.

Study Design.
Community-based cross-sectional study design was used.

Source Population.
The source population was all mothers/caretakers to children aged 12-23 months pair in Debre Markos town.

Study Population.
The study population included all mothers/caretakers to children aged 12-23 months pair in Debre Markos town who fulfill the inclusion criteria.

Inclusion Criteria.
The inclusion criteria were all mothers/caretakers to children aged 12-23 months pair who are permanent residents (for at least six months) in Debre Markos town.

Exclusion Criteria
(i) Mothers/caretakers with missed immunization card (ii) Mentally/critically ill mothers/caretakers (iii) Not volunteering to participate/being unable to give required information 3.8. Sample Size. The sample size was determined by using single proportion formula, by using prevalence of complete immunization coverage in children as 22.9% from previous study conducted in Ethiopia [8], 95% CI, and 10% nonresponse rate. Hence, the sample size calculated was 298.
3.9. Sampling Procedure. There were seven kebeles in the town. All the seven kebeles were included in the study. At each kebele, households are selected by using systematic random sampling. The sample in each kebele is allocated proportional to the number of households. When two or more eligible mothers/caretakers to child pair were found, only one was included by lottery method.

Instrument and Personnel.
Structured interviewer administered questionnaire was used to collect the data. It was adapted from previous researches done on similar title [4,7,9]. The questionnaire was first prepared in English and translated to Amharic and back to English to maintain the consistency of the content of the instrument. Seven nursing students participated as data collectors.
3.11. Data Quality Control. Orientation and training were given to data collectors regarding purpose of study and ethical issues. Pretest was done on 5% of the actual study subjects out of the study area. After pretest, vague terms and questions were discarded. The result of pretest is not included in the study result.

Data
Processing and Analysis. The data was cleaned, coded, and entered in EpiData version 3.1 and transferred to SPSS version 20.0 for analysis. Descriptive and inferential statistics were used to present the data. Descriptive statistics like frequency and percentage were used to summarize the sociodemographic characteristics of the study participants. Variables showed statistical significant in bivariate analysis, that is, value < 0.05, and were entered in the final model of multivariate analysis. And value of less than 0.05 in multivariate analysis was considered as statistically significant at 95% CI.

Operational Definitions
Complete Vaccination. A child who received ten basic vaccines (one dose of BCG, three doses each of the DPT-HepB-Hib (pentavalent), three doses of polio vaccines, three doses of PCV, two doses of Rota vaccine, and one dose of measles vaccine before first birth date) is considered to be completely vaccinated.

Incomplete Vaccination.
A child who received some of the vaccines and/or not the full dose of the ten vaccines before Advances in Public Health 3    good health, prevention of infections, advice from professionals, and being compulsory, 272 (96.1%), 247 (87.3%), 17 (6%), and 2 (0.7%), respectively.

Factors Associated with Complete Immunization.
Relation to the child, occupational status, child's sex, type of pregnancy, place of delivery, ANC follow-up, knowledge of time of vaccination schedule, and distance from vaccination site were found to be significant on bivariate analysis. And child's sex, type of pregnancy, ANC follow-up and distance from vaccination site were found to be associated with complete vaccination on multivariate analysis (Table 5).

Discussion
In this study, it was found that 91.7% of children were completely vaccinated, 6.6% were partially vaccinated, and 1.7% were not vaccinated at all and there is 5% overall dropout rate. The result showed increased vaccination coverage when compared to previous studies done in different areas [4,7]. This may be due to increasing access of vaccination and community awareness from time to time.
Adjusting for other factors, child's sex was significantly associated with complete immunization. Males were three times more likely to be completely vaccinated 3.24 (1.16-9.04) when compared to females. The result is in line with previous study done in northern Ethiopia [5]. But in a study done in Iran, no correlation was detected between gender and immunization status [10]. The difference might from cultural differences between study populations.
The type of pregnancy was another factor which predicts complete immunization. The odds of wanted pregnancy were two times more likely for complete immunization 2.89 (1.17-7.17) than unwanted pregnancy. The study is not congruent with previous study which showed no statistical association between immunization and wanted pregnancy [11].
Another factor that affects complete immunization was ANC follow-up during pregnancy. Mothers who had at least two ANC follow-ups during pregnancy were four times more likely to vaccinate 4.04 (1.35-12.06) their children when compared to mothers who did not have ANC followup during pregnancy. This is in line with a study done previously in which there was inverse correlation between delayed vaccination and the number of periodical visits of health centers [12]. This might be because mothers during ANC visit would receive counseling and education about the importance of postnatal visits and activities.
Distance of home from vaccination site was another predictive factor for children complete vaccination. Parents who are less than or equal to twenty minutes away from vaccination sites were three times more likely to vaccinate their children 3.38 (1.29-8.86) than parents who are more than twenty minutes away. But in a study done previously, no 6 Advances in Public Health correlation was detected between vaccination delay time and distance from health centers [12].

Conclusion and Recommendation
There was relatively high immunization coverage in the study. About 91.7% were completely vaccinated, 6.6% were partially vaccinated, and 5 (1.7%) were not vaccinated at all and the overall dropout rate was 5%.
Child's sex, ANC follow-up during pregnancy, type of pregnancy. and distance from health institution were factors associated with complete vaccination of children.
Preventing unwanted pregnancy through family planning and promoting ANC and postnatal follow-up should be strengthened.
Vaccination sites should also be further expanded and accessible to the community. And health education should also be given largely to the community about the need to vaccinate all children.

Conflicts of Interest
The authors declare that they have no conflicts of interest.