Determinants of incomplete immunization among children age 12-23 months in Southwest, Ethiopia: Case Control Study

Background Vaccination is recognized as an important immunization tool which is used in preventing and eradicating communicable diseases. Even though increase in global vaccination coverage, many children in the world particularly in low resource countries still are left unvaccinated and it remains to be a public health problem. So the main objective of this study was to identify determinants of incomplete vaccination among children 12-23 months of age in Semen Bench district, Bench Maji Zone, Southwest Ethiopia, 2018. Methods A community based unmatched case-control study was undertaken among randomly selected children aged 12 to 23 months and with a total sample size of 312 (104 cases and 208 controls). Simple random sampling was used to get representative cases and controls. Data was collected using a structured questionnaire. Data was entered into Epi Inof version 7 and analyzed using SPSS version 21 statistical software. Bivariate and multiple logistic regression analyses were done to identify independent factors for incomplete immunization status of children. P values <0.05 with 95% confidence level were used to declare statistical significance Results From the total selected 104 cases and 208 controls, all of the cases and controls participated in the study with a response rate of 100% .The multivariable analysis indicated that respondents having no antenatal visit [AOR=8.3(95%CI; 1.87-36.91], giving birth in home [AOR=4.5(95%CI; 1.411-14.27], respondents having no postnatal visit [AOR=4.2(95%CI; 1.67-10.41], and respondent having inconvenient appointment time [AOR=3.44(95% CI:1.65-7.16)] were some of the variables continued to have statistically significant factors of incomplete vaccination. Conclusion This study was identified some of the factors associated with incomplete vaccination. In order to decrease neonatal mortality resulted from communicable diseases Strengthen antenatal care visit and promoting postnatal care service utilization and institutional delivery and providing convenient and appropriates appointment time is very important in addition to this it is crucial that, local programmatic intervention should be strengthened to promote awareness of the community on the importance of Vaccination.

2 Abstract Background Vaccination is recognized as an important immunization tool which is used in preventing and eradicating communicable diseases. Even though increase in global vaccination coverage, many children in the world particularly in low resource countries still are left unvaccinated and it remains to be a public health problem. So the main objective of this study was to identify determinants of incomplete vaccination among children 12-23 months of age in Semen Bench district, Bench Maji Zone, Southwest Ethiopia, 2018. Methods A community based unmatched case-control study was undertaken among randomly selected children aged 12 to 23 months and with a total sample size of 312 (104 cases and 208 controls). Simple random sampling was used to get representative cases and controls. Data was collected using a structured questionnaire. Data was entered into Epi Inof version 7 and analyzed using SPSS version 21 statistical software. Bivariate and multiple logistic regression analyses were done to identify independent factors for incomplete immunization status of children. P values <0.05 with 95% confidence level were used to declare statistical significance Results From the total selected 104 cases and 208 controls, all of the cases and controls participated in the study with a response rate of 100% . The

Background
Immunization is one of the most worthwhile public health interventions to prevent child mortality and morbidity (1). It is considered as a globally proven strategy for childhood intervention. Each year, 3 immunization averts more than 2 million vaccine-preventable deaths globally (2,3). Despite this enormous use, immunization coverage in developing countries has reported to being low. In 2011 alone, 1.5 million children died from Vaccine Preventable Diseases (VPDs) (4,5,6,(7)(8).
In 2013, coverage of third-dose diphtheria, tetanus, and pertussis vaccine (DTP3) among children aged < 12 months was 84% globally, ranging from 75% in the African Region to 96% in the Western Pacific and European Regions. About 14.8 million (68%) children who did not receive the DTP3 vaccine during the first year of life lived in 10 countries including Ethiopia (9).
Even though vaccination offers greater benefits of health, well-being, and survival of children than any other interventions, vaccine-preventable diseases are still responsible for about 25% of deaths of under-five children. Most of the deaths are from diarrheal diseases, acute respiratory infections, and measles. More than a quarter of these are reported in low and middle-income countries including Ethiopia (10,11,12,13,14) In Ethiopia, a routine immunization program was launched by providing six traditional antigens in 1980. The Program was revised subsequently and was capable of providing 10 vaccines to under 1 year of age at the moment. In addition to the traditional vaccines that are given without any charge, new vaccines are continuously introduced into the Immunization Program. Recently, the program has successfully introduced additional antigens which have resulted in the protection of millions of children from vaccine-preventable diseases (15). Based on the Ethiopian demographic health survey (EDHS 2016 report) around 39% of children aged between 12 to 23 months receive all basic vaccination and in the study area 24.4% of children aged between 12-23 months have not received all basic vaccination (15)(16). In Ethiopia Measles is one of the five major causes of childhood illnesses, which together contribute to 70% of under-five morbidity and mortality (15).
According to the WHO measles burden estimator, Ethiopia contributes to 46% of the cases and 51% of the deaths from measles among eight eastern African countries (5,9,10). Previous studies done in Ethiopia indicated that the main factors lead to incomplete vaccination are multiple such as mothers age, educational status of father, mother's knowledge on vaccination, fear of side effects, shortage of vaccines in the health facility, inconvenient appointment time, and political instability (15,17) 4 High immunization coverage is essential to control and eventually eliminate vaccine-preventable diseases (VPDs) and understanding the level of immunization among children is vital to design appropriate interventions. This study was therefore conducted to determine and identify factors associated with incomplete vaccination among children aged 12-23 months

Study design and setting
A community-based unmatched case-control study was conducted from February to March 2018 in Semen Bench district, Bench Majii Zone, South west Ethiopia. The district is known for frequent outbreaks of vaccine-preventable diseases, especially measles. It has 31 kebeles and an estimated total population of 138,556. The study was conducted in seven kebeles (the smallest administrative units in Ethiopia

Source population
All household with mothers/care givers who had children in the age group 12-23 months of age residing in semen Bench district for both cases and controls.

Study population
Study population for cases: Selected eligible households with mothers/care givers who had children in the age group of 12 to 23 months who did not complete the recommended vaccination.
Study population for controls: Selected eligible households with mothers/care givers who had children in the age group of 12 to 23 months who completed the recommended vaccination.

Sample Size Determination
Sample size was determined by using Stat Calc program of the Epi Info version 7; Used to calculate the sample size with exposure among controls is 84.4% from previous study in Tigray region (18) , and 5% marginal error, 95% confidence interval, power of 80%, case to control ratio of 1:2 and 10% of non-response rate was considered. Calculated sample size in all Independent (exposure) variables are considered and place of residence is chosen as an independent variable since it gave maximum sample size as compared to other exposure variables. The larger sample size was 282+30 (10% nonresponse rate) =312 (104 cases and 208 controls)

Sampling Technique and Procedures
Simple Random sampling technique was used to reach household level. The seven districts were selected by simple random sampling (lottery method). And the calculated sample size was allocated proportionally according to their population. From the two years family folder list of cases and Poor knowledge: Those mothers /respondents who scored below mean score of the knowledge questions.
Good knowledge: Those mothers /respondents who scored equal and above mean score of the knowledge questions.
Before undertaking data collection, the questionnaire was pretested on other similar population taking 5 % of the total sample outside the study area and necessary modifications were made. The questionnaire was prepared originally in English and translated to the local language. The questionnaire was further translated from local language to English to check for consistency. The 6 primary respondent was the mother of the child. In case of her absence, the questionnaire could also be completed by the father or another adult in the household acting as the primary caregiver. The data were collected by trained, diploma midwife, fluent in local language, using the structured questionnaire translated to local language. Three health professionals with bachelor's degree in health supervised the data collection process. Before data collection, the data collectors and supervisors were recruited and training was given on the objective of the study and techniques of data collection for two days

Data Processing and Analysis
Data were entered using EPI-Info version 7 and analyzed using SPSS-version 21 statistical software.
Descriptive statistics were used to summarize the data, and a bivariable analysis was carried out to describe associations between exposure variables and childhood immunization status and assessed by chi-square and odds ratio with a significance level of p-value ≤ 0.05. Variables with p-value ≤ 0.25 were included in the final model. In the multivariable analysis, additionally model fitness was checked by Hosmer and Lemeshow goodness of test and p-value ≤ 0.05 was applied to identify independent factors of incomplete childhood immunization.

Socio-Demographic Characteristics of respondent
A total of 208 controls and 104 cases (with 100% response rate) were included in the study. Majority of respondents for controls 198(95.2%) and for cases 85 (81.7%) were mothers. With regard to religion most care takers/mothers for cases and controls were protestant which accounts 85(81.7%) and 169(81.3%) respectively. Regarding to maternal educational status 82.7% of cases and 61.1% of controls were no formal education ( Table 1)

Respondents characteristics of health-related service utilization
All cases and controls of respondents reported that there is vaccination site in their district. Of the mothers/ care takers 50(48.1%) of cases and 33(15.9%) of controls were turned home without getting vaccination for their child due to inconvenient appointment time. Majority of respondents were two to four birth orders which comprises 67.3% of cases and 63.9% of controls. Regarding ANC visits 75(72.1%) and 208(98.6%) of cases and controls have ANC visits respectively ( Table 2).

Mothers or care takers Knowledge about vaccination
Majority of mothers/ care takers was knowledgeable about vaccination which accounts 88 (84.6%) for cases and 202 (97.1%) for controls (Table 3).

Factors Associated with incomplete vaccination
Multiple logistic regression analyses identified that relationship of mother/care taker with child, father education, Postnatal care (PNC), place of birth, Antenatal care (ANC) visit, and Inconvenient appointment time were independent predictors that had statistically significant predictors with incomplete vaccination.
This study shows that Antenatal care visit is predictor of incomplete vaccination, those who had no  Table 4).

Discussion
The finding of this study showed that having antenatal care visit was statistically significant predictors on multivariate analysis. The finding of this study is consistent with the same study Conducted in Mozambique, wonago district and other part of Ethiopia respectively (19,20,21).
Similarly giving birth at home was found to be an independent factor that leads to incomplete vaccination status of the child. The finding of this study is consistent with the same study conducted 8 other parts of Ethiopia (20.21) and Nepal (22). The explanation related to this may be due to those mothers who give birth at health institution are more like to use the health service than those mothers who gave birth in the home.
In this study father's educational status was an independent predictor for incomplete vaccination.
This may be due to as educational level increase; health seeking behavior of family may possibly increase and this in turn may have positive impact on child vaccination. The finding of this study showed that mother's educational status is not significant predictor for incomplete vaccination. This is contrary to the study conducted in Jamaica which revealed that having maternal education level collage and above were more likely vaccinate child than others (23).
Inconvenient appointment time were significant predictors of incomplete vaccination. This is also consistent with other study conducted in Ethiopia (20, 21) In this study children and mothers/ care takers relationship was significant predictor of incomplete vaccination. This may be due to a mother being able to give a good care for her own child including vaccinating her child timely and completely. In contrast to this study, study conducted in Jamaica revealed that there is no association between mothers/care taker and child Vaccination (23).

Conclusions
The finding of this study showed that absence of antenatal care follows up, absence of postnatal care attendance, having home delivery, low level of father educational status and inconvenient appointment time was significant predictor of incomplete vaccination. Based on the finding of the study we recommend that governmental and non-governmental organization working in neonatal and child health improvement should intervene and strengthened to promote awareness of the community on the importance of post-natal care, anti-natal care and institutional delivery is the way to optimize children's complete vaccination status.

Ethics approval and consent to participate
Ethical clearance was obtained from Arba Minch University, college of medicine and health science, Institutional Ethical Review Board and was communicated to the Bench District Health Bureau. Prior to data collection, the purpose of the study was clearly explained and written consent was obtained from the mothers

Availability of data and materials
The datasets used and/or analyzed during the current study available from the corresponding author on reasonable request.

Competing interests
The authors have no conflicts of interest to declare for this study. Tables.pdf