Magnitude and Associated Factors of Delayed Immunization Among Children Aged 11 -23 Months in Edagahamus Town, Tigray, Ethiopia, 2018.

Background: Delayed immunization is a major public health problem that is associated with vaccine-preventable disease epidemics. In Ethiopia, many children don’t receive the benefits of age-appropriate immunization; thus more than 90% of child deaths are largely due to preventable communicable diseases. Therefore, the aim of this study to assess the magnitude and factors associated with delayed immunization among 12 -23 months old children in Edagahamus Town, Tigray, Ethiopia, and 2018 G.C. Methods: A community-based Cross-Sectional study was carried out on July1-30, 2018. A simple random sampling method was used to select study participants. Information was collected using a structured, pre-tested questionnaire. The date of vaccinations was obtained from children’s immunization cards and timeliness assessed based on the recommended age ranges. Data were entered and analyzed using SPSS version 20.0. Variable with P-value < 0.2 in bivariate was exported to multivariate. The strength of association was identified using the odds ratio with a 95 % confidence interval (CI) and the P-value of <0.05 in multivariate was taken statistically significant. Results: In this study, the overall magnitude of delayed immunization was 29.5% (95%CI 26.7-45). Private firm work of mothers (AOR=0.205 95% CI 0.068-0.617), Mothers who attend tertiary education (AOR 0.169, 95% CI 0.032-0.882), and secondary education (AOR 0.269, 95% CI 0.114-0.636) had the protective effect of delayed immunization. But sickness of a child (AOR= 11.8, 95% CI 6.16-22.65) was a risk for delayed immunization. Conclusions: From the study, it is concluded that the magnitude of delayed immunization for children aged 12-23 months is high (29.5%) in Edagahamus. Delayed immunizations of children were predicted by the Mother's occupation,

education, and Mother's consideration in the child's wellness to take the vaccine.

Background
Vaccine-preventable diseases cause over three million childhood deaths each year globally especially in developing countries (1,2). From the nearly 8.8million yearly deaths of under-five children greater than 20% are due to Vaccine-preventable diseases (VPD) (3). VPD is a major cause of morbidity and mortality in children under five years of age in developing countries including Ethiopia (4). Ethiopia has experienced many outbreaks and hence morbidity and mortality from VPD (5,6).
According to EDHS 2016; childhood mortality rates have declined since 2000, despite that, infant and under-5 mortality rate in Ethiopia was 48/1000 and 67/1000 respectively (7). Immunization is the most important public health interference for VPD (8). It presently averts more than 2.5 million deaths every year in all age groups from diphtheria, tetanus, pertussis (whooping cough), and measles (9,10).In Ethiopia nearly 4 in 10 children aged 12-23 months have received all eight basic vaccinations; single doses of BCG and measles and three doses for each of Pentavalent, PCV, Rota and polio vaccine. Immunization is a key element of the health extension program package. However, timely and full vaccination coverage has not been completed in Ethiopia as planned, thus more than 90% of child deaths are largely due to preventable communicable diseases and nutritional disorders (20).
In Edagahamus, the Expanded Program on Immunization (EPI) schedule is not applied as National advice for the timing of delivery, as a result, many children don't receive the benefits of timely and age-appropriate immunization. So, improving timely and age-appropriate immunization delivery would require a better understanding of reasons for the delay (18). Delays in receiving immunization have been reported globally (21). In the United States of America, up to 40 percent of parents delay or refuse their children's vaccine (16). 63.3 % of the Gambian children had a delay in the mentioned age range to receive at least one of the studied vaccines(1). In Uganda, less than half of all children received all vaccines within the recommended time (22). According to different literatures, factors that are associated with delayed immunization includes; marital status, educational status, occupation, income, service accessibility, transportation, distance, place of birth, birth order, number of children in the household, sickness of the child, Forget/don't know the due date and so on (1,19,22,23).
Today, parents' vaccine hesitancy may have been increased by celebrities' public airing of their concerns about vaccines (31)(32)(33). Parents commonly mention the fear of side effects as a reason for not vaccinating their children; eg, in Liberia, Somalia, Armenia. In some cases, an older sibling experience of side effects leads to parents refused vaccination for younger children. Little is known about delayed immunization and as per the investigators; no studies conducted to assess delayed immunization. Therefore, this study aimed to assess the magnitude and factors associated with delayed immunization among 12 -23 months old children in Edagahamus.

Study setting
A community-based cross-sectional study was conducted from July 1-30/ 2018 at Edagahamus city, Tigray regional state of Ethiopia. Edagahamus is founded in the eastern zone of Tigray, wereda Saesie Tsaida Amba; which is located 885 Km north of the Ethiopian capital city of Addis Ababa,105 Km east of the Tigray capital city Mekelle and around 20 Km near to Adigrat. Edagahamus is divided into four kebeles and the total population was 21,993; from those 10,031 were male and 11,962 were female (2006/2012 census). There is only one health center in Edagahamus and the total number of under two-year children is 795.

Participants
Sampled children aged 12 -23 months old living in Edagahamus and who fulfill the inclusion criteria were taken as the study population. Households that have one living child aged between 12-23 months old who have the vaccination card are included, While Households who have children aged between 12-23 months old who do not complete their vaccination (drop out) were excluded.

Sample size determination and sampling technique
The sample size was calculated using a single population proportion formula with the following assumption: Prevalence of children's who had delayed vaccination in Gambia =63.3% (1),95% of confidence interval(1.96), 5% margin of sampling error tolerated, 10% of non-response rate, then the final sample size are 393. A simple random sampling method was used to select study subjects using a sampling frame obtained from the health extension workers. The mothers' identity and the households' numbers that are used by the Health extension workers were used to identify the selected households. In the case of two or more mothers having a child's in the same household, one mother was selected using the lottery method.
First, a list of all eligible participants was prepared in excel after obtained from the health extension workers. Then, the random number was generated using OpenEpi software and marked the selected one against the excel. Finally, each eligible study participant was contacted through the house to house visits. A second visit was done in case a mother was absent in the house during the first visit. If the mother is not available for the second time, a neighbor's mother with a child was contacted.
Samples were allocated to each kebeles using a proportion to the size allocation.

Independent Variables
Socio-demographic and economic factors, Maternal/caregiver factors, Child's factors, and Service-related factors.

Data collection tools and techniques
Data was collected by using an interviewer-administered and structured questionnaire adapted from WHO survey questions and related pieces of literature according to the objectives (1,19,22,23,30). The questionnaire includes Sociodemographic and economic factors, Maternal/caregiver factors, Child's factors, and Service-related factors.

Data quality assurance and control
Five Midwife data collectors and supervisors were recruited from another area outside of the study site and they were given training for three days. The supervisors followed the process of data collection daily, checked the data completeness consistency and communicate with principal investigators daily.

Data Processing and Analysis
data was coded, cleaned, recorded and entered into Epi info 7and finally export to SPSS version 20.00 for analysis. Simple descriptive summary statistics were done.
Tables, statements, charts, and graphs were used to present the result of the analyzed data. Associations between independent and dependent variables were analyzed first using bivariate logistic regression analysis. Variables that had p<0.2 on bivariate analysis were entered into multivariable logistic regression analysis.
The statistical association between the different independent variables to the dependent variable was measured using OR, AOR, 95% CI and P-values <0.05 was considered statistically significant.

Socio-demographic Character of the study participants
A total of 393 mothers of children aged between 12-23 months old were interviewed from four kebeles, with a response rate of 100%. Out of the total study subjects, 222(56.5%) have children aged 11-17 months, while 171(43.5%) were aged 18-24 months. The mean (+SD) age of the children was 17(+ 6) months old. Female children were 208 (52.9%) of the total study subjects. The age range of mothers included in the study was 17-43 years, which is a childbearing age range. The mean (+ SD) age of the mothers was 29.4 (+5.3) years old. (Table 1)

Maternity-related characteristics
Overall 327(83.2%) of mothers know the immunization schedule. A total of 278 (70.7%) of the mothers got health education, particularly about immunization during antenatal and postnatal care while they were pregnant and after the birth of the child. (Table 2)

Service-related characteristics
Overall 44(11.2%) returned home due to a lack of vaccine. About 246(62.6%) mothers get advice during the immunization period on adverse events following vaccination ( Table 3). For the third dose of Pentavalent, PCV and polio vaccines 26 (6.6%) of the respondents presented after the age of 24 weeks and delayed for up to two months.

The magnitude of age untimely vaccination
For the measles vaccine, 29(7.3%) of the children presented after the age of 11 months and 5.2% and 1.4% were delayed for up to three and seven months respectively(figure 1).

Factors associated with delayed immunization
In the bivariate logistic regression maternal occupation, marital status, educational status, lack of vaccines, lack of appointment, sickness of the child's and "don't know" the due date was associated with delayed immunization at p-the value of < 0.2. In multivariate logistic regression analysis sickness of the child, mothers' occupation and education have a significant association. Children's of mothers who were employed at private occupations were less likely to delay their vaccines (AOR 0.205 95% CI 0.068-0.617) compared to children's of mothers who were a housewife. Mothers who had tertiary education (AOR 0.169, 95% CI 0.032-0.882) and secondary education (AOR 0.269, 95% CI 0.114-0.636) were less likely to delay their infant's immunization compared to those mothers with no education. child sickness in the appointment day were more likely to delay (AOR 11.36, 95% CI 4.68-27.55) than those healthy.

Discussion
This study aimed to assess the magnitude and factors associated with immunization delay among 12-23 months old children. In this study, the overall prevalence of delayed immunization among the study participants was found to be 29.5% (95% CI 26.7%-45%). other countries' experiences show the overall prevalence of delayed immunization can vary. For example, the study done in the Gambia showed a prevalence of 63.3 % (1) and the study was done in Atlanta showed 25.8% (24). This difference might be attributed to the difference in educational background, degree of knowledge towards immunization, and the difference in the study population. However, it is similar to the study done among Norwegian children 44.7 % (23). This is justified due to the similarity in the study population, Vaccinations are mainly provided by public health nurses and all services are voluntary and free of charge. The occupation was significantly associated with delayed vaccination; in this study private firm work of mothers was positively associated with timeliness, which is similar to the study done among Gambian children (1). The reasons may be multiple, for example, better knowledge about vaccination and time management and housewife women might be fully engaged at home with domestic tasks hence they tend to forget their children's vaccination appointments. The educational status of the mother/caretaker was a predictor for delayed child immunization; in this study maternal education beyond the secondary level was positively associated with timeliness, Similar to the study done in Nigeria(21), Gambia(1) and Iran (19). This is attributed because highly educated mothers are more willing to seeking care than other mothers. The sickness of the children was also associated with delayed vaccination similar to the study done in Nigeria and Shenzhen, China (21,30). This may be around missed opportunities to vaccinate with mild illnesses. Socioeconomic status and the number of children in the households were not predictors for delayed child's immunization in this study, which is different from studies in Gambia and Uganda, which indicates income-related factors hindered utilization of immunization services so that children's with several siblings were more likely to have untimely vaccinations, that higher cost and demands can easily discourage to vaccinate their children's (1,22). This difference could be explained by the fact that free service for immunization is implementing in Ethiopia so that higher costs and demands were not a problem among families participated in this study.

Conclusions
From the study, it is concluded that the magnitude of Delayed immunization for children aged 12-23 months is high (29.5%) in Edagahamus. Delayed immunizations of children were predicted by the Mother's occupation, and education which had the protective effect of delay immunization and consideration of the mother the child was too ill to undertake vaccination when it was due was a risk for delayed immunization. Therefore it is important to consider education as vital for the attainment of full immunization which intern raises the need of the community and creates maternal awareness about the importance of child immunization. There is a need to disseminate information on the importance of mothers' occupation that most of the mothers with domestic works have more likely to delay immunization. Edagahamus City, and selected kebeles written consent was obtained from all participants after they informed on the purpose of the study. Information's obtained from individuals participants was kept secure and confidential. Names and other identifying data of respondents were made by using code throughout the study process to obtain confidentiality. Finally, data were collected according to the standard questionnaire prepared.

Availability of data and materials
The datasets used during the current study available from the corresponding author on reasonable request (Additional file 1).
MG designed the study, performed statistical analysis, and drafted the paper. TG, SS, BH, and MK participated in paper writing. All authors contribute to the data analysis and read and approved the final paper.     Figure 1 Timely versus delayed immunization among 11-23 months old children in Edagahamus, Tigra