Background
Immunisation remains the most cost-effective intervention in public health. Globally, vaccination currently prevents 2–3 million deaths annually as more than a billion children were vaccinated in the past decade [
1]. There has been a significant reduction in childhood mortalities related to vaccine-preventable diseases (VPDs) from 5.1 million in 1990 to 1.8 million in 2017 [
2]. The World Health Organisation (WHO) defines immunisation as the process whereby a person is made immune or resistant to infection, typically by the administration of a vaccine [
3] through a process of giving antigenic material. Vaccination coverage on the other hand is defined by the WHO as “the proportion of a given population that has been vaccinated in a given period. It accounts for each vaccine and, for multi-dose vaccines, for each dose received” [
4].
In May 2012, the World Health Assembly developed the Global Vaccine Action Plan (GVAP) to help avert millions of childhood mortality attributed to VPDs through equal access to vaccines by 2020 and beyond to tackle inequalities associated with access to life-saving vaccines, especially in Low and Middle Income Countries (LMICs) [
5,
6]. Despite the WHO efforts, the coverage is still below the global target [
1,
2,
7]. Studies on immunisation coverage in Africa have shown improved but suboptimal coverage in most settings [
8‐
10]. Therefore, most countries are not in line with reaching the SDG target 3.2 of reducing childhood mortality [
11].
Uganda has also succeeded in reducing child mortality, however, the level is still high at 40.564 deaths per 1000 live births as compared to the global target as of 2022 [
12]. Most of the under-5 deaths are due to VPDs making it a public health concern. In 1983, the Ugandan National Expanded Program on Immunisation (UNEPI) was established in partnership with Global Alliance for Vaccines and Immunisation (GAVI) to achieve vaccination goals; following the vaccination schedule on S1 Table
1 [
13]. The immunisation services are offered by trained healthcare workers in health facilities and through selected community outreaches. Periodical supplementary immunisation is carried out during outbreaks as well. The immunisation services aim to completely immunise children and women of childbearing age against Diphtheria, Hepatitis B infection, Polio, Whooping cough, Tuberculosis, Tetanus, Measles, Haemophilus influenza and Pneumococcal Infections whilst 10-year-old females and women of reproductive age are immunised against Human Papilloma Virus that causes Cancer of the Cervix and Tetanus [
14] (S1 Table
1).
Despite immense efforts by the government of Uganda and its developmental partners to increase immunisation coverage, a decline in immunisation coverage has been noticed. A 90% vaccine coverage is the national acceptable target however, only BCG (96%) is at the national acceptable level whilst the other vaccines are below the accepted levels [
15] (S2 Fig.
1).
According to the WHO data on childhood immunisation coverage in Uganda, there has been a further decline in immunisation coverage in the past years and it has significantly dropped from 90% to below 80% as of 2022.
The full immunisation status of children cannot be assessed without discussing the factors that determine immunisation. As modernization grows with increasing urbanisation, more people tend to live in urban areas with many being marginalised in the slums and unable to access immunisation services. This is coupled with challenges in reaching remote rural populations with difficulty in technological development for the cold chain into the bargain [
16].
Most studies have shown that the educational level of the parents, awareness of the availability of immunisation services, health-seeking behaviour, wealth index, place of residence, parents’ educational level and occupation and distance to the service delivery points are the main factors contributing to low coverage of full immunisation in children. In Sub-Saharan African settings, these individuals and contextual factors play an important role in improving the immunisation status of children.
Studies in Sub-Saharan Africa comparing coverage of full immunisation status of children in urban cities, slums and rural settlements showed that slums have better coverage compared to rural settings [
17,
18]. Other studies showed significantly poor coverage of full childhood immunisation status in both slums and rural areas [
19‐
21]. Many works of literature, however, studied coverage of full immunisation status in urban settings comparing it to the rural area with urban areas having better coverage [
10,
22‐
28]. Literature has also shown that children from educated parents [
10,
23,
28‐
30], parents with access to information from mass media [
9,
31], and parents who are employed coupled [
32,
33] with high wealth index [
34] had higher chances of being fully immunised as compared to their counterparts.
Therefore, this study compares the differences in full immunisation status among children aged 0 to 23 months living in slums of Kampala city and Iganga District as rural districts in Uganda. It also highlighted some of the factors that influence the completion of all immunisation doses in both settings.
Discussions/analysis
This paper compared the state of immunisation coverage in the slums of Kampala the capital city of Uganda with coverage in the rural-based district of Iganga in Eastern Uganda for children aged of 0–23 months. Additionally, the study investigated how full immunisation status is influenced by a range of factors grouped as external environment, predisposing, and enabling in nature. Just over half of the children (53%) were fully immunised against vaccine-preventable diseases which was considerably low compared to the global target of 90% coverage [
44] which could be responsible for high morbidity and mortality rates among infants and children.
External environment (area of residence) influences a child’s full immunisation status
This study has shown that children living in slums had a higher chance of being fully immunised as compared to children in rural areas. This could be because slum dwellers had a higher percentage of hospital deliveries. Studies have shown that children delivered at a health facility usually have a full immunisation status [
6]. A similar finding was made in Nigeria where it was established that slum dwellers had better coverage than rural settlers [
17]. A recent study in India comparing urban and rural areas showed a significant difference with urban areas having a higher coverage. The study further compared the slums with the rural area and concurred that slum dwellers had better coverage despite their poor socioeconomic status [
18].
The higher chance of full immunisation in slums compared to rural could also be due to the easier access to immunisation services in urban areas than the rural area as the rural settlements might be hard to reach. As discussed above, 20% of the rural settlers live more than 5 km from a health facility. It could also be because slum settlers had information on new vaccines. Therefore, they might have education on information on immunisation and its importance.
Role of area of residence
Furthermore, full immunisation status for individual vaccines was also influenced by the child’s area of residence with children living in slums having a better coverage of the individual vaccines as compared to the rural dwellers. However, there was poor uptake of the 3rd doses of most vaccines in both settlements. This indicates a significant dropout rate of the vaccines. The study showed a huge gap (44% decline) in slum vaccine coverage between BCG birth dose vaccine (97,9%) and measles vaccine (53.8%) given at 9 months. A low uptake of measles vaccine at 9 months is a challenge in obtaining full immunisation coverage. The reason in this study could be attributed to inadequate access to mass media as most mothers have not heard about immunisation campaigns. Therefore, campaigns on vaccination need to be improved to improve parents’ consciousness of vaccine uptake. Similar results were seen in research done in the slums of Nairobi [
19].
Likewise, a drop in coverage was noticed at 8.8%, 16.9%, 20.5% and 23.6% from the first to the 3rd dose of Polio vaccine, Penta, Pneumo and Rota vaccines respectively. The rural areas even had a higher dropout rate in the individual vaccines mentioned. A similar problem has been seen in rural Hoima District, Uganda showing a low coverage of measles as compared to the BCG birth dose vaccine and a dropout rate of 28.5% on DPT (between DPT 1 and 3) [
21]. These high dropout rates and gaps indicate a high prevalence of missed opportunities in childhood vaccination which is a global public health concern and an obstacle to attaining the Sustainable Development Goal of reducing child mortality. The knowledge of parents on the importance of immunisation is the key driver in achieving full immunisation. The uptake of new vaccines in both settings was also assessed and there was significantly low coverage of Pneumococcal vaccine and Rota vaccine with worse uptake in the rural area. This could be due to the poor dissemination of messages on the availabilities of immunisation services in the communities and the importance of having children take them. Both slums and rural areas need promotions and activities geared towards educating mothers on the importance of having their children receive all the vaccines on time. The lack of sensitization which is shown as parents not having adequate knowledge of childhood immunisation might be an important factor in both poor uptake of new vaccines and the high dropout rate of the other vaccine.
One might expect slums to have a better full childhood immunisation coverage than the rural areas as it is in the urban area and we can argue that it should be closer to healthcare resources. However, the evidence presented in this study shows the contrary. The slum dwellers are marginalised and have little to no access to services. Due to the rapid urbanisation of Kampala city, many people searching for better livelihood tend to live in slums as it is more affordable and accessible for the poor and unemployed [
45]. There is no plan in place to organise the needs of the slum dwellers. The lack of services and individual attitudes become contributing factors to poor full-childhood immunisation in slums as the purpose of living shifts to daily survival instead of providing the merits of responsible and organised living, planning, compliance and proper service delivery [
46]. This can be a leading factor in hindering progress in achieving good health. Therefore both slums and rural areas have a very low uptake of childhood vaccines.
Predisposing factors to attaining full immunisation status
Continuing with the predisposing factors, it showed that male children tend to be fully immunised compared to female children. The mother’s marital status was not statistically significant in this study. However, other studies have shown the contrary that married women tend to have their children fully immunised as well. This is because married women tend to have better healthcare-seeking behaviour [
47,
48]. Moreover, the involvement of the partner could contribute to the financial support and the utilisation of healthcare.
Enabling factors to attain full immunisation status
Finally, the enabling factors were mostly associated with full immunisation. Children without health cards had a higher chance of full immunisation. Children reported not having a health card but received immunisation could be because of a recall bias of the parents. The findings further suggest that parents’ educational attainment had no impact on full immunisation and that could be the reason why mothers that were market vendors had higher chances of immunising their children compared to those in a professional job. This could be because the market vendors are self-employed and can therefore have time to immunise their children.
Limitations of this study
A limited set of variables were used to study the determinants of immunisation coverage. Factors such as mother’s antenatal visits could not be assessed. Maternal recall was used to determine whether a child was fully immunised or not and this increases the chances of recall bias in the study. Unlike a longitudinal study, the data was collected at one point in time. With this type of study, we cannot prove causality [
35].
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