Introduction

Expanded Program on Immunisation (EPI) is one of the most important public health interventions used to reduce child morbidity and mortality associated with infectious diseases1. It forms a key building block for the healthcare delivery systems by which globally, an estimated 3 million deaths are prevented by vaccination each year through its successful implementation1,2. Vaccines are one of the safest and most cost-effective interventions and vaccination coverage is mentioned as part of Sustainable Development Goal 3 which aims at eliminating preventable deaths of newborns and under five children by 20303. Despite its importance, currently, 19 million children do not receive basic vaccines and of this, 60% are from low and middle-income countries5,6.

In Ethiopia, two out of ten (19%) children aged 12–23 months had not received any vaccines7. Ethiopia is among the countries with the highest rates of vaccine-preventable diseases (VPDs), contributing significantly to child mortality rates and 16% of under-five mortality in Ethiopia is attributed to vaccine-preventable diseases, such as measles, pneumonia, and diarrheal diseases, which could be prevented with timely vaccinations8,9,10. According to the 2016 Ethiopian Demographic Health Survey, 39% of children aged 12–23 months were vaccinated, with rates varying greatly across geographical regions and only 22% were vaccinated at the appropriate age10,11,12. Immunisation coverage in Ethiopia was 44% in 2019, referring to children who received the full schedule of basic vaccines (BCG, DPT, polio, and measles), ranging from the highest in Addis Ababa (83%) and Afar (20%).

To improve immunisation coverage in Ethiopia, interventions such as implementing an integrated health extension package, training health extension workers, and expanding primary healthcare services were carried out13. Access to quality healthcare includes different factors, such as availability, acceptability and affordability14,15. Numerous studies had revealed that low immunisation coverage can be attributed to a variety of factors, including family socioeconomic and demographic characteristics, access to maternal health services, knowledge of immunisation, and maternal satisfaction. Each of these factors plays a crucial role in enhancing the quality of immunisation16,17,18,19.

The quality of immunisation service depends on the service accessibility, waiting time and, availability of vaccines20. In Ethiopia, one of the EPI strategy objectives is to improve the quality of child immunisation21. Accordingly, knowledge of the benefits of child vaccination, and the health facilities’ readiness to provide the vaccination service is important to improve the quality of immunisation service22. To ensure the quality of immunisation of vaccine safety, which is proper handling and storage, safe vaccine administration (trained staff) and safe waste removal are required23.

Effective coverage is one of the approaches which can be used to monitor health system performance by including the use, needs and quality of healthcare services24. Although there are ways to measure effective coverage for health care services, quality-adjusted coverage is preferable to measure maternal and child health services as it has the potential to provide an overall estimate of effective coverage in global, national, and local settings25.

This study was conducted to assess the effective coverage of child immunisation in Ethiopia. To our knowledge, it is the first study on the effective coverage of immunisation in Ethiopia. The findings will help track the quality of immunisation and the performance of the health system, contributing to improvements in the overall effectiveness of healthcare delivery.

Methods

Study area

Ethiopia is a federal state located in the horn of Africa which is divided into 9 sub-regions and two city administrations. Ethiopia has three tire health systems (primary, secondary and tertiary). The primary level of care includes primary hospitals which provide emergency surgical services, including caesarean sections, and blood transfusion services, health centers which serve an average population of 100,000 people and five health posts in each health center catchment area. The secondary level contains the general hospital which provides inpatient and ambulatory services and patients referred from primary hospitals. The last tier system is the tertiary level which encompass the specialized hospitals that serves an average of 5 million people including referral from general hospitals26.

Data source

In this study, we have linked two nationally representative community based and facility-based datasets. The Ethiopian Demographic and Health Survey (EDHS) 2019 provided individual-level data on immunisation coverage across the population, offering insights into vaccination rates and coverage patterns at the individual level, allowing for a detailed analysis of coverage rates at both regional and national levels. The other dataset used was SPA (Service Provision Assessment) which is part of the DHS program and SPA 2020–2021 is a facility-based survey which collects data on quality of care and service availability. This dataset includes records from health facilities, detailing factors such as the availability of vaccines, quality of healthcare services, and adherence to clinical guidelines. By examining the health facility records from ESPA, we were able to assess the quality of health services provided, which allowed us to calculate and interpret key indicators of healthcare quality. By combining individual immunisation data from EDHS 2019 with facility-based quality metrics from ESPA 2021–2022, we created a comprehensive assessment of both coverage and quality of immunisation services in Ethiopia. The EDHS holds data that is publicly available via DHS at https://dhsprogram.com/.

Measure of variable

Coverage variable

Child immunisation was recorded based on the information from their immunization card and the mother’s report. A child was considered fully immunized if either the card was available or the mother provided confirmation27. Full child immunisation was defined as receiving all essential vaccines with in the age group of 12–23 months. A child is considered fully immunised if they received one dose of BCG vaccine for tuberculosis, three doses of the pentavalent vaccine (DPT-HepB-Hib), three dose vaccines for polio and one dose of measles7.

Quality of care variables

There are three dimensions used to measure the quality of service, these are structure, process, and outcome28. We use the structural component of child immunisation service to assess the quality which, refers to the facility’s readiness to give immunisation services including the availability of trained personnel, equipment, medical supplies and commodities29. We used 14 indicators to generate the quality of health facilities (Supplementary Table 1).

Child immunisation service readiness scores were calculated using averages based on the WHO guideline30. The readiness of immunisation had three domain (staff and guideline, equipment and, medicines and commodities), Staff and guidelines variable staff were recoded as “yes” if the staff were trained and “no” if they did not receive any training. Guidelines were recorded as “yes” if observed and “no” if none were available or reported but not observed. Equipment variables were coded as “yes” if they were observed and valid and else recoded as “no”. Medicines and commodities variables were recoded as “yes” if they were observed and at least one valid and else recoded as “no”25. The inactivated polio vaccine was excluded from the study due to the absence of records in the ESPA dataset.

The readiness score was calculated as a sum of the available items of each domain, divided by the total number of items in the domain, finally multiplied by 10030.

$$\:Quality\:\left(readiness\right)=\frac{sum\:of\:avilable\:items}{total\:number\:of\:items}\:*100\:$$

The sociodemographic variables

We have used sociodemographic variables to describe the participants which were extracted from the kids’ record (KR) of the EDHS 2019 dataset. The residence was classified as urban and rural. Women’s education was classified as no education, primary, secondary and higher. Wealth index was categorized into five levels (poorest, poor, middle, rich, and richest). These scores were assigned based on the quantity and types of consumer goods a household possesses, such as a television, bicycle, or car, along with housing features like the source of drinking water, toilet facilities, and flooring materials29. We have recoded age, marital status and religion as literatures. Mother’s age were classified as “15–24”, “25–35” and “36–49”33. Marital status was recorded as currently married and unmarried (single /divorced /separated/widowed)34. Religion was recoded as Orthodox, Muslim, Protestant and Other (Catholic, traditional and other)33.

Data management and analysis

The data was cleaned, and missing values were managed using a guide to DHS statistics. The data were weighted using sampling weight to restore the representativeness of the survey.

To determine immunisation coverage, we utilized the Kids Record (KR) file from the Ethiopia Demographic and Health Survey (EDHS), focusing on a sample of 1,028 children aged 12–23 months who were a live at the time of the survey. However, to maintain data consistency, we excluded the Tigray region from our analysis due to the absence of corresponding records in the Ethiopia Service Provision Assessment (ESPA) dataset. Accordingly, by removing 93 observations from Tigray, the final unweighted sample size was 915. For the quality measurement, we used the health facility records from the Ethiopia Service Provision Assessment (ESPA) dataset, which includes data from 1,158 health facilities across the country. For our analysis, we selected 774 facilities that specifically provide immunization services to ensure our focus aligned with relevant healthcare delivery points.

We have used administrative boundary linkage method to link the two datasets31,32. First, we calculated the proportion of immunisation coverage for each region, enabling us to match the regional average coverage with facilities located within the same area. This matching process facilitated a region-specific analysis of immunisation coverage across healthcare facilities, thereby enhancing the accuracy of the coverage estimates. This approach provided a clearer overview of quality-adjusted immunisation coverage across available regions in Ethiopia, aligning with the data completeness of the ESPA dataset.

The effective coverage of immunisation was calculated by multiplying the quality of the health facility (readiness) with the immunisation coverage. The formula was adopted from the WHO effective coverage framework25,33.

Effective coverage = Quality of the health service * crude coverage.

We use Stata 17 for analysis. Descriptive statistics was done to describe the socioeconomic and demographic characteristics of respondents and the facility characteristics. Additionally, sensitivity analyses were conducted to evaluate the impact of heavily skewed regions on the effective coverage of child immunisation. Finally, the sociodemographic characteristics of respondents and the characteristics of the facilities were presented using tables and graphs.

Results

The study included 951 women with live children aged 12–23 months. Among them, 30.4% were aged 15–24, 56.8% were 25–35, and 12.7% were 36–49 years old. Additionally, the majority of participants (69.5%) resided in rural areas. (Table 1).

Table 1 Socioeconomic and demographic characteristics of participants EDHS 2019 (n = 951).
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Health facility characteristics

A total of 774 health facilities that provide immunisation services were included. A large proportion of the health facilities were from rural areas (58%), and most of health facilities were hospitals (35%) (Table 2).

Table 2 Health facilities characteristics across regions in Ethiopian SPA 2021–2022 (n = 774).
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Crude coverage of immunisation

The crude coverage of immunisation services in Ethiopia was 39.59% (95% CI: 36.47, 42.70), ranges from 19.18% (95% CI: 0.00, 41.74) in Afar to 87.39% (95% CI: 75.67, 99.12) in Addis Ababa (Fig. 1).

Fig. 1
figure 1

Crude coverage of immunisation across administrative regions.

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Quality

A total of 43.38% (95%CI: 41.60, 45.16) of health facilities, with a regional variation from 36.37% (95%CI: 32.66, 40.09) in the Southern Nations, Nationalities, and Peoples’ Region (SNNPR) to 61.63% (95%CI: 56.49, 66.76) in Addis Ababa, were equipped with adequate staff and guidelines. Additionally, 79.15% (95%CI: 76.46, 81.84) of health facilities had sufficient medicines and commodities, with the lowest availability in Afar at 67.65% (95%CI: 51.90, 83.39) and the highest in Addis Ababa at 92.56% (95%CI: 86.11, 99.00). Furthermore, 87.71% (95%CI: 86.58, 88.83) of facilities are equipped with necessary medical equipment, ranging from 81.72% (95%CI: 79.48, 83.96) to 97.67% (95%CI: 95.77, 99.57) in Addis Ababa (Table 3).

Table 3 Quality of health facilities in each domain by regional Ethiopian SPA 2020–2021.
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The overall score for quality of immunisation service is 82% (95% CI: 80.44,83.51). The quality ranges from 74.6% (95% CI: 71.42,77.81) in SNNPE to 95.5% (95% CI: 92.52,98.51) in Addis Ababa. The quality of immunisation also varies with the type of health facilities, clinics had the highest quality (91.4% (95% CI: 79.86,100)) while health posts had lower quality 64.1%(95% CI: 60.78,67.50) (Table 4).

Table 4 Quality of health facilities by facility type Ethiopian SPA 2020–2021.
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According to areas of health facilities, facilities in urban areas had higher quality (89% (95%CI: 87.65, 90.83)) than the facilities in rural areas (77% (95%CI:74.55,79.06)). Moreover, the quality of immunisation varies with the management authority of Health facilities, private facilities had the highest quality (90% (95% CI: 85.35, 95.36)) and government facilities score the lowest quality (82% (95% CI: 80.06, 83.22)) (Fig. 2).

Fig. 2
figure 2

Immunisation service quality by health facility characteristics.

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Effective coverage

The national effective coverage of immunisation was 34.3% (95% CI: 32.99, 35.50) with a large variation in different regions, ranging from 14.8% (95%CI: 13.03,16.63) in Afar to 83.5% (95%CI: 80.85,86.09) in Addis Ababa. Addis Ababa had the highest effective coverage of immunisation service 83.5% (95%CI: 80.85,86.09) with a 3.9% difference from its crude coverage (87.4% (95%CI: 75.67,99.12)) (Table 5). Sensitivity analyses results were provided in a supplementary file (Supplementary file 1).

Table 5 Effective coverage of immunisation service in Ethiopia.
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Discussion

The effective coverage of child immunisation was 34.3% with a large variation in different regions, ranging from 14.8% in Afar to in Addis Ababa. Addis Ababa had the highest effective coverage of immunisation service 83.5% with a 3.9% difference from its crude coverage (87.4%). This might be due to a geographical variation, distance from the health institution, and a lack of health care infrastructure, particularly in Afar and Somali regions characterized by pastoralist nomadic people. Another cause might be the high population density, particularly in an urban administrative metropolis like Addis Ababa, as well as maternal education, which promotes knowledge about the necessity of immunisation, and educated mothers pick health care facilities that result in better health for their children.

The crude coverage of immunisation services was 39.6%. This showed that despite the efforts to increase the quality of immunisation services, there is a huge gap in both the crude and effective coverage of immunisation services. This finding was lower than a study conducted in Nepal with 90%34 crude coverage of all the childhood vaccines, in Mexico with 51% and in Nicaragua with 70%35, in India with 76%36, in kenya with 66.6%37, and in Senegalese with 70.96%38. The discrepancy might be due to socio-demographic, economic, accessibility, and availability of health infrastructure and other commodities. The other possible explanation might be due to the educational status of the mother, who has great awareness of the time, the importance, and the side effects of vaccination39.

This study also assessed the overall score for the quality of immunisation service (service readiness.) which was 82%. This finding was lower than a study conducted in North Gondar Zone (90.3%)39. There was a discrepancy in the overall quality of immunisation service among regions, areas, and types of health facilities, city administrations, and the management authority of Health facilities.

The quality of child immunisation services was often influenced by the availability of key components such as trained staff, medicines, and necessary equipment. This study showed that 43.38% of health facilities had adequate staff and guideline, with significant regional disparities ranging from 36.37% in the Southern Nations, Nationalities, and Peoples’ Region (SNNPR) to 61.63% in Addis Ababa. Additionally, 79.15% of facilities had access to necessary medicines and commodities, with Addis Ababa having the highest rate (92.56%) compared to Afar (67.65%). Moreover, 87.71% of health facilities were adequately equipped, with regional variations from 81.72 to 97.67% in Addis Ababa. These findings aligned with other studies that highlight regional inequalities in healthcare service delivery, particularly in immunization12,40,41. This might be due to urban centers like Addis Ababa consistently perform better than rural regions due to resource availability and infrastructure. Studies also showed that resourced health systems ensure the effectiveness of immunisation programs and reducing vaccine-preventable diseases42.

The discrepancy among regional level, the quality of immunisation service ranged from 74.6% in SNNPE to 95.5% in Addis Ababa. This might be due to the availability of trained staff in urbanized cities, accessibility, and adequate availability of equipment and commodities. Across areas and types of health facilities, the quality of immunisation services also varied. According to the area of health facilities, facilities in urban areas had higher quality (89.2%) than that of the facilities in rural areas (76.8%). This might be because of easy availability and accessibility of health infrastructures, equipment, and medical supplies and commodities43,44.

On the type of health facilities, clinics had the highest quality (91.4%) while health posts had lower quality 64.1%. The possible explanation might be high or medium-level health facilities had updated and well-trained staff, who possess the skill competencies needed to provide child immunisation, while in low-level facilities like health posts service training is not easily available and accessible45. Another explanation might be better accessibility and availability of resources, including human power46.

Strength and limitation

This study had many strengths, of this, we used the DHS dataset which had a large sample size. We used the recent EDHS dataset 2019. The study also had limitations, the first limitation is that we used the facility readiness (structural component) to adjust the effective coverage of immunisation, other components were not included. The second limitation was that we used regions to match the dataset, people might get the service from other region facilities and it may cause misclassification. The last limitation was that the Tigray region was not included as the SPA dataset had no record for facilities in Tigray.

Conclusion

The study revealed that there was low effective coverage of immunisation in Ethiopia. The effective coverage was lower in the Afar and Somali regions. Government facilities and facilities in rural areas had lower-quality immunisation services. Facilities in SNNPE and Afar region had low-quality immunisation. Policymakers and responsible bodies should focus on improving the quality of government facilities and the facilities in rural areas and the SNNPE and Afar region. Additionally, stakeholders could increase the number of trained staff and guidelines across all regions, as well as improve the availability of medicines and commodities, particularly in areas with low supply, such as Afar.