Timely completion of vaccination and its determinants among children in northwest, Ethiopia: a multilevel analysis

Vaccine preventable diseases contribute substantially to under five mortality as well as morbidity [1]. Hence, immunization has become one of the major contributors to public health globally as it prevents communicable disease, particularly in children. Evidence shows that 29% of deaths among under five children are vaccine preventable [2] and being fully vaccinated is associated with 22% lower mortality in children [3].

Immunization averts an estimated 2 to 3 million deaths every year worldwide. However, despite the tremendous efforts made so far, vaccine preventable diseases remain a major health problem among children in developing countries including Ethiopia [4‐7].

Completion and timeliness of routine vaccination as recommended by the World Health Organization (WHO) are very crucial for maximum protection of children against specific infections [8]. To effectively control vaccine preventable diseases (VPDs), high immunization coverage is required with a targeted coverage level of 90% recommended by the WHO. In terms of control and prevention of childhood infectious diseases, achieving high vaccination coverage is a necessary; but insufficient indicator to assess the success of immunization program. In order to successfully control and eliminate vaccine-preventable infectious diseases, age appropriate vaccine coverage has to be achieved and maintained [9‐12].

However, maintaining a high performance of an immunization program and its quality is challenging, with non-attendance and delays to vaccination appointments remaining a key challenge in developing countries [13, 14]. Worldwide in 2018, about 116.3 million infants (86%) received three doses of diphtheria-tetanus-pertussis (DTP3) vaccine, protecting them against infectious diseases. On the other hand, an estimated 19.4 million infants worldwide were not reached with routine immunization services of which around 60% of these children live in 10 countries, including Ethiopia [15]. As a result, substantial proportions of children in many countries still fail to benefit from all basic vaccines and vaccine preventable diseases still pose a public health risk with the highest rates of child mortality still in Sub-Saharan Africa [16, 17].

Ethiopia launched the immunization program in 1980 and currently provides 11 antigens at birth, 6 weeks, 10 weeks, 14 weeks and 9 months. Despite the fact that immunization services are offered free of charge, full vaccination coverage in Ethiopia is significantly lower than the global target. The 2016 Ethiopian Demographic and Health Survey (EDHS) report showed that only 39% of children received all basic vaccinations [18] and the 2019 mini EDHS report also indicated that the full vaccination coverage has reached 43% with steady increase in vaccination coverage over time [19]. Findings from studies conducted in different settings of Ethiopia showed a wide range coverage of full vaccination from 48.8 to 91.7% [20‐26]. On the other hand, the incomplete vaccination coverage ranged from 20.3 to 45.5% [20, 23, 24].

Multiple assessments also reveal that despite relatively high vaccination coverage, there was a gap in the timeliness of children vaccination with substantial delay in age-appropriate vaccination demonstrating that high vaccination coverage does not imply that children are vaccinated according to the schedule [16, 27‐36].

Currently, the timing of vaccine administration has received increasing attention in many countries, especially when the level of vaccination coverage is close to that needed for protective herd immunity [10, 29, 37]. Although many studies have measured full vaccination coverage, studies on timely vaccination completion are rare in developing countries particularly in Sub- Saharan Africa (SSA) [16, 31].

To date, timeliness is not routinely used as an indicator to evaluate immunization programs in Ethiopia. Similarly, several studies had examined and documented the vaccination coverage for childhood immunization in Ethiopia with which timeliness had received less consideration [13, 19, 22, 24, 38]. Therefore, this study aimed to determine the coverage and associated factors for timely completion of vaccination among children in Gondar city administration, Northwest, Ethiopia.

Timely vaccination is very important to get the maximum benefit of the vaccine. As the health system is mostly focusing on the completion of vaccines, timely completion of recommended vaccines is important for evaluating the effectiveness of immunization programs in Ethiopia. In this study a total of 774 children nested within 10 clusters were included in the analysis after excluding 38 unverifiable records. The analysis showed that timely vaccination coverage is low in the study area. The results of the study also indicated that individual and community level factors were significantly associated with on-time full vaccination.

The findings of this study indicated that around two-third of children were fully vaccinated which is far behind the national target [5]. This finding is also relatively lower than the findings of studies in Dessie [21], Woldia [22] and Markos [26] towns. This could be explained by the difference in information source for outcome measurement where we have used objective measures to ascertain vaccination status of children from the EPI cards and health facility registers only. In this study, one third of children had not completed their vaccination and the coverage rate for specific vaccines declined for subsequent doses of vaccines with high dropout rates. This finding corroborates with other evidences where missing measles and third doses of polio and pentavalent vaccine were the main reason for not being fully vaccinated [3, 24, 43]. In addition, the study indicated different coverage’s for specific vaccines provided in the same vaccination visits. This finding is in line with other studies [21, 26]. This might be related with unavailability of some specific vaccines or supplies especially for the newly introduced vaccines like Rota and PCV during vaccination sessions. Service availability and readiness assessment report of 2018 also showed that availability of vaccines in health facilities ranges between 28 and 30% [59].

In terms of timeliness, we found that that almost two-third of the children were not vaccinated on-time either being early or late from the recommended time schedules. These findings corroborate the findings of other studies most of which reported higher proportion of delays in child vaccinations [10, 13, 27, 33, 49, 60‐64] This study also pointed out that only half of fully vaccinated children were timely for all the vaccine doses. This indicates that merely relying on vaccination coverage overestimates population immunity, as it does not account for delays in protection and extended susceptibility to preventable diseases. Another reports in the literature also concur that timely vaccination coverage is a better performance metric for routine immunization services than crude vaccination rates alone [53, 61]. As such, untimely vaccinations are likely to contribute greatly to the preventable disease burden in Ethiopia, allowing for transmission among those in the age group at which they are the most vulnerable to severe disease.

In the present study timely vaccination coverage was not only low, but also it declines as one goes from penta I to penta III and measles vaccine doses which is consistent with other evidences [32, 45, 46]. This might be due to increased caregiver’s workload with other activities while the child gets older and thereby might not remember vaccination appointments of their children.

This study also found that a substantial number of children started their routine vaccination much earlier than the recommended age. Similar result has been reported elsewhere [43]. We found a high proportion of children vaccinated before 9 months of age for measles which may be related with the measles open vial policy issues in which, the measles multi-dose vial has not been opened daily unless sufficient numbers of children were found in the vaccination site; be it in a static or outreach setting. According to the Advisory Committee on Immunization Practice recommendation, these earlier vaccine doses leads to low sero-conversion rates with less child protection from vaccine-preventable disease and the vaccine dose should be repeated [42].

This study also demonstrated that there was a delay in all vaccine types showing that many Ethiopian children are receiving their vaccinations later than recommended, leaving them unnecessarily vulnerable to disease for extended periods. The implication of delay in receipt of vaccines is that a pool of children with incomplete or no immunization may build up [62]. The presence of such a pool of susceptible children predisposes to outbreaks of vaccine preventable diseases [13].

This study finally assessed the individual and community level factors associated with on-time full vaccination. At the individual level the variables age of caregiver, educational status, household wealth index, ANC and PNC service utilization were significantly associated with on-time full vaccination. The study showed that, as the caregivers get older the odds of timely full vaccination decreases. This finding is consistent with findings from Belgium [10], China [30] and Saudi Arabia [37]. This difference could be explained by the reason that the younger caregiver would possibly have a better utilization of health care which may lead to an increased probability of vaccinating their child on-time [30]. On the other hand no significant effect was reported from studies in Burkina Faso [31] Uganda [13] and Pakistan [52].

On-time full vaccination coverage was higher among children of caregivers with high educational level. Several studies also support the finding of higher educational level being related to timely adherence to the vaccination schedules [13, 16, 31, 32, 50, 51, 63, 65]. The possible reason for this may be related with the fact that the low education level can hinder the caregiver’s communication with health workers and might influence caregiver’s awareness to seek and take advantage of public health services including child vaccination.

Household wealth index was also found to be a significant predictor of on-time full vaccination in this study, with a better timeliness of vaccination among children from the richest households. This finding is consistent with findings from other countries [10, 13, 16, 50, 51, 61, 66]. Though immunization services in Ethiopia are completely free of charge, the indirect cost of vaccination, such as income loss and transportation cost, might be associated with the low demand for vaccination especially for poorest households [50].

ANC visit of four or more at the health facility predicts better timely completion of child vaccination as it has been reported from other study settings [13, 61, 65]. It is possible that mothers who attended ANC visits at health facilities may be more frequent users of health facilities and services including vaccination for children. In this study on-time full vaccination coverage was high among children whose mothers attended postnatal care [43]. This is expected as they can get counselling about vaccination during PNC visits and their children have more chances of getting the vaccines than those who do not make any follow-up contact for PNC service.

At community level, the variables distance to the vaccination site and place of vaccination were significantly associated while place of residence didn’t show significant association with on-time full vaccination. In this study, distance to the vaccination site was negatively associated with on-time full vaccination. This finding is consistent with studies in Burkina Faso [31], China [30] and Tanzania [36]. Thus, this further strengthened the argument that the time spent to reach the vaccination site expenses a high opportunity cost to caregivers by creating the need for multiple visits, especially when vaccine vials were not opened for a small number of children like BCG and measles vaccines.

The findings of this study also indicated that timely vaccination was more likely if the child was vaccinated in hospitals than health posts. This study is consistent with a study in Lebanon [60]. This may reflect that health services, mainly having a better utilization of vaccination services, were more preferable and accessible to caregivers. National reports also indicated that child vaccination as an outreach service was not commonly offered on daily basis which is the case at health post level [59, 67].

In our study, place of residence have no significant association with on-time full vaccination. In Ethiopia, urban areas might have easier access to health services and better transportation available whereas the introduction of the health extension program might have increased access to vaccinations in rural areas with well-established rural outreach immunization efforts, which may account for the insignificant results in this study. This finding corroborates with a finding from Pakistan where residence has no effect on timeliness of vaccination [52]. This finding is inconsistent with other findings from Bangladesh [50], Vietnam [51] and Nigeria [68] where children from urban areas have better timeliness for vaccination. This was justified by the reason that health facilities are more proximal to clients in the urban community than the rural community. On contrary, in a study from Burkina Faso children from rural have better timeliness for Penta III and measles vaccination [31]. It was explained that although the urban area has a better health infrastructure compared to the surrounding villages, caregivers need to take their children to the health facilities by their own initiative, while rural villages are visited by an outreach vaccination team each month.

In addition, we found evidence of clustering effects of timely full vaccination at community (Kebele) level, such that children from the same communities tended to have similar vaccination status. This suggests that public health programs designed to improve timeliness of vaccination should address people and the communities in which they live [69].

The results of this study should be interpreted taking in to account the following limitations. Though Gondar city administration has urban and rural kebeles, the study was restricted to children having a history of routine vaccination in one city administration. So, the study findings might not be generalizable to children in all regions across Ethiopia. Our study participants might have also introduced recall bias in remembering the frequency of maternal health service utilization factors and the reasons for untimely vaccinations. To reduce recall bias, we ascertained vaccination outcomes objectively from EPI cards and EPI registers of health facilities. Despite these limitations, this study is a community-based survey that would be more representative of the children population. Similarly, the analysis considered the clustered nature of the data by applying multi-level modeling.

In this study, full vaccination coverage was relatively low and untimely vaccination was found to be high. At individual level the variables caregiver’s age, caregiver’s education, household wealth index, ANC and PNC service utilization were the significant factors affecting on-time full vaccination. In addition, at community level the variables distance to vaccination site and place of vaccination were the significant predictors of on-time full vaccination. Therefore, health facility vaccinators should focus on timeliness of vaccination to minimize early and delayed administration of vaccines. Moreover, targeted interventions should be implemented among the older, uneducated and caregivers with low socio-economic status. In addition, strengthening the quality of ANC and PNC services is also important. At health post level, emphasis should be given for daily vaccination service provision.