Immunization Coverage and its determinants in Children Aged 12-23 Months in Basrah

Background: Immunization is one of the most important programmes which contributed to the prevention of major childhood diseases. A high coverage rate is desirable for the effectiveness of this programme. Objectives: This study aimed to assess the level of immunization coverage rate among children aged 12 to 23 months in Basrah during 2014-2015. Also, to explore the vaccination dropout rate and the causes of partially immunization. Methods: A cross sectional survey was done in 30 clusters that followed the World Health Organization cluster sampling technique. Data were collected via direct interview with 300 mothers using an Arabic language questionnaire and the data were analyzed using SPSS programme. Results: The vaccination coverage rate in this study was 80.7% and the dropout rate was 19.3%, which is rather high while the main causes of the dropout were difficulties facing mothers' attendance to Primary Health Care centers (50%) and lack of information (31%). Conclusions: The results of the current study showed that although the coverage rate of immunization was adequate, the dropout rate was high and the important reasons for that were inadequate awareness and inconvenience timing for mothers. In addition, literacy status and occupation of mothers, child birth order and family type were other reasons.


INTRODUCTION
mmunization is often cited as being one of the greatest public health achievements of the 20 th century. [1,2] Effective immunization requires population coverage levels of 90 to 95% depending upon the vaccine-preventable disease. [3] The coverage is estimated by the late I vaccine doses achieved among children in the first year of their age. [4,5]  Assessing immunization coverage helps to evaluate progress in achieving programme objectives and in improving service delivery. [8] In addition, evaluation of immunization coverage provides evidence whether substantial progress towards achieving vaccination targets is being made. [9] Vaccination coverage is defined as the proportion of a given population that has been vaccinated in a given time period. It is estimated for each vaccine and, for multidose vaccines, for each dose received (e.g., diphtheria-tetanus-Pertussis-containing vaccine (DTP1, DTP2)). It is usually presented as a percentage out of targeted children. [8] The capacity of the health system to complete the immunization course for a child is estimated based on the dropout rate indicator between the first dose and the last dose of the vaccine at first year of age of the children. The maximum acceptable dropout rate is 10%. Globally, higher rates indicate inefficiency of the health service, service discontinuity at fixed posts, lack of information to mothers about returning for the follow up doses and a lack of subsequent visits by outreach or mobile teams. [10] Marital status, sex, and possessing of children card were other contributing factors of dropout rates. [11] Immunization programmes are monitored using two methods: an administrative institutionbased method and through community-based surveys. [12] This study aimed to assess the level of immunization coverage rate among children aged 12 to 23 months in Basrah during 2014-2015. Also, to explore the vaccination dropout rate and the causes of partial immunization.

Study design
A community-based cross sectional descriptive survey with a multistage sampling technique was conducted in Basrah province during the period between 3 rd and 14 th of April, 2016 on 30 randomly selected clusters, where 300 children (10 for each cluster) aged 12-23 months were studied for vaccination coverage.

Study population
According to Ministry of Planning 2015, the estimated total population of Basrah province was 2,818,000 and the target population for routine immunization was 418,000 (14% of total population). [13] Sample size The minimum sample size of 300 children was estimated following the standard procedure for using WHO cluster sampling for assessment of immunization coverage. [12] A total of 30 clusters in the community were demarcated based on its population and sector-wise distribution.

Sampling technique
In the first stage, all the eight administrative districts in Basrah were included. In the second stage, a list of the settlements in each of the district was obtained and 30 of settlements were selected randomly (each settlement was taken as a cluster). The third stage involved the selection of households; the first household was selected randomly in each cluster and every next household was studied in a sequence, until a total of 10 eligible children in the age group of 12-23 months were covered. On reaching the selected household, the mother of the eligible child was interviewed. If no child belonging to the target population was found, next households were checked till an eligible child was found.

Data collection
Data collection was carried out by direct interview with mothers using a modified Arabic form of validated WHO sample research questionnaire on EPI and an interview guide to collect information regarding sociodemographic parameters, status of immunization of children, and reasons for nonadherence. Age of children and status of immunization were confirmed by vaccination cards and they were determined as: Complete Immunization for the purpose of this study: Children have received Bacillus Calmette-Guerin (BCG), Measles, and three doses of DPT, hepatitis B, and Oral Polio Vaccine (OPV) each. Partial/Incomplete Immunization: Children who have received at least one (but not all) of the above mentioned vaccines. Unimmunized Children: Children who have not received any vaccine.

Ethical issues
Permission was taken from Basrah Health Directorate and a verbal consent was obtained from the participants. Mothers of children who were found not immunized were advised to complete the immunization schedule.

Data management
The obtained data were analyzed with SPSS version 19.0. In testing for associations, cross tabulation was done and chi-squared or Fisher Exact Fisher Test has been used for qualitative variables. The level of significance was established at P-value ≤ 0.05.

RESULTS
The respondent mothers were mostly in the age category between 21-30 years. Illiteracy appeared in considerable proportion (12.3%) among mothers. However, graduates exceed this level (14.0%). Seventeen percent of the respondents were employed. The rest were essentially housewives and 65% of families were multigenerational house (Table-1). The study included 300 children with equal male: female ratio. The order of the involved children is essentially equally distributed from first to more than 4 th . Health facility deliveries of the children in the sample represent 62% (Table-2).  (Table-3-B). Mother's age, gender of the child and place of delivery do not seem to have an influence of the coverage rate of vaccination. On the other hand, mother's education, mother's occupation, family type and birth order of the child affected coverage (Table-4).

*Fisher Exact Test
Causes of failure to complete immunization schedule were segregated into three categories: Obstacles (50%), lack of information (31%) and lack of motivation (19%) ( Table-5). Family problem including illness of mother 2 3.4 Vaccine not available 1 1.7 18  Further analysis showed that access to immunization is allowed to 97% of the reported children. Dropout from DPT1 to Measles is 16.8% compared to that from BCG to Measles (19.3%) and ending with coverage of 80.7% revealing a modest utilization problem. None of the children was found to have zero immunization.

DISCUSSION
Immunization, a component of primary prevention, plays a pivotal role in the prevention of a number of diseases affecting children, the most vulnerable population. Improvement in the immunization status not only enhances the health of the people but also the economic stability of the country. [8] The World Health Organization (WHO) states that by 2020, coverage of target populations should reach at least 90% national vaccination coverage and at least 80% vaccination coverage in every district or equivalent administrative unit for all vaccines in national immunization programmes. [14] Although the immunization coverage target (90%), according to WHO regulation, is not attained in this study, it was fairly satisfactory as compared to general coverage rate in Iraq 2013 where the vaccination coverage was 63%.
[8] One of the strengths of this study is that the immunization status of each subject was confirmed by immunization cards. The use of immunization cards to assess coverage is necessary to verify the immunization status of a child as both over and underestimation are possible depending on the maternal tendencies exhibited with regards to immunizations. [15] Reports show that some developing countries have achieved optimal immunization coverage, while others are making great strides in doing so. [16] The consequence of suboptimal immunization coverage is low herd immunity with continued circulation of vaccine preventable diseases in the community. Herd immunity is improved by immunizing eligible children in the community and this subsequently results in lower incidence of vaccine preventable diseases [17] . There were variations in the coverage rate for individual vaccines. It is noteworthy that three of the antigens (BCG, OPV0, and HepB1) recorded100%, while (DTP1, OPV1, and HepB2) recorded 97% and DTP2,OPV2 recorded 90%.The proximity of the time of delivery to the vaccine schedule for obtaining the earlier vaccines may explain the high rates of coverage for these vaccines. The lowest coverage rates were recorded for DTP3, OPV3, HepB3 (85.7%) and Measles vaccine (80.7%) reflecting poor compliance for vaccines scheduled for administration later in infancy.
Generally, these levels are more than the national figures. [8,9] Dropout rates were also measured to determine immunization programme continuity showing the number of the children who start but fail to complete the immunization process. All dropout rates between different vaccines groups were above the accepted level 10%. [8] The high and variable dropout rates between vaccines may be related to the presence of obstacles encountered by 50% with the commonest obstacle to immunization being mother too busy (27.6%). Mothers also need to be educated on the importance of immunization and the need for subsequent doses of vaccines, as lack of information (31%) was also an important reason for incomplete immunization. These factors were studied in a similar setting in India and revealed identical causes of dropout except a cause of the child being ill. [1] Concerning socioeconomic factors that predict immunization coverage, it was observed in this study that mothers with some education were more likely to have fully immunized their children compared with those that had no formal education. Similar result was found by Vikram 2012. [19] Higher immunization coverage was also more common among children of employed mothers. The female literacy level in the study population was low as about one third of the mothers had either no formal education or just can read and write. This is higher than the nationally detected figure of 22% of illiteracy by Iraq Women Integrated Social and Health Survey. [19] The female literacy level in a community needs to be optimal as educated mothers utilize child health services better (including immunization) and this has been linked positively with child survival. Children from single generational families were more likely to complete immunization than those from multigenerational homes and children of the 1 st and 2 nd birth order than those of 3 rd order and above. Several studies have corroborated findings of a larger family size and later birth order as being associated with poor immunization status of children. This may be related to socioeconomic and domestic pressures of a large family due to time pressures and cost of transportation for each immunization for each child, especially if health care facilities are not in close proximity. [1,10,18] In conclusion, the rate of immunization of the children was adequate and there was significant association between literacy status and occupation of mothers, child birth order and family type with the immunization status of children. The probable reasons of partial immunization were inadequate awareness and inconvenience for mothers. Measures which are likely to improve and maintain high coverage rate include, health education, improvement of female education, reminders of timing and outreach follow up of dropped out children. In addition, periodic household surveys are useful means to support the EPI.