Factors associated with zero-dose status among children aged 12–23 months, Uganda, August to September, 2024

Summary

Background: GAVI defines zero-dose children as those who have not received Diphtheria-Pertusis-Tetanus1 (DPT1), which represents a gap in immunization programs and a marker of inequity in access to essential health services. In Uganda, DPT1 coverage exceeds 90%. However, there are regional variations due to health system factors, leaving pockets of unvaccinated children and posing an increased risk of outbreaks. We determined the prevalence and factors associated with zero-dose status among children aged 12–23 months in Uganda.
Methods: We conducted a cross-sectional household survey in all 15 regions of Uganda. We sampled 2,254 children aged 12–23 months using multi-stage cluster sampling. Data were collected through caregiver interviews using a standard questionnaire and review of vaccination cards. Weighted prevalence estimates were calculated. Multivariable logistic regression was applied to assess factors associated with zero-dose status among the children.
Results: The overall prevalence of zero-dose status was 9.1%. The highest zero-dose prevalence was observed in South Central (17%) and Bunyoro (17%), while the lowest was in Acholi (3.9%) and Kigezi (2%). The factors significantly associated with zero-dose status included absence of information on the next appointment (aOR=18; 95% CI=8.5–38), lack of trust in vaccines (aOR=7.1; 95% CI=1.5–34), having above secondary education (aOR=6.6; 95% CI=1.5–28), and unfavorable family norms (aOR=3.5; 95% CI=1.7–6.9).
Conclusion: Despite overall high national coverage, nearly 1 in 10 Ugandan children aged 12–23 months remain unvaccinated with DPT1, with substantial regional disparities. Zero-dose status is driven by a combination of caregiver characteristics, social norms, and systemic barriers. We recommend strengthening community engagement by leveraging VHTs and local leaders to create awareness and reminders on next appointments through media platforms. Promoting the use of immunization champions to build caregiver trust in vaccines and celebrating positive societal practices on immunization to achieve equitable coverage.

Background

Immunization, preventing 2.5 million child deaths worldwide annually, is one of the most successful public health interventions. (1). It is key in attainment of the United Nations Sustainable Development Goal 3.2, which aims to reduce under-five mortality to less than 25/1000 live births by 2030 (1, 2). The diphtheria-tetanus-pertussis (DPT) containing vaccine plays a critical role in protecting children against three life-threatening but preventable diseases (3). These are Diphtheria, Tetanus, and Pertussis (4). Without DPT vaccination, these diseases pose a significant risk of child morbidity and mortality. The World Health Organization (WHO) defines zero-dose children as those who have not received even a single dose of the DPT vaccine by the age of 12 months (5).

Zero-dose status in children aged 12–23 months is influenced by various factors, including maternal education, access to healthcare facilities, and place of delivery (6). Additionally, community-related challenges such as vaccine hesitancy, misinformation, lack of awareness, and cultural beliefs also contribute to non-immunization (7). These missed vaccinations not only put individual children at risk but also weaken herd immunity, leading to potential outbreaks of vaccine-preventable diseases (7). Although Uganda has adopted several strategies to improve immunization coverage, the persistence of zero-dose children suggests that systemic and contextual barriers remain inadequately addressed. We determined the prevalence and identified the factors associated with zero-dose status among children aged 12–23 months in Uganda.

Methods

We conducted a community-based cross-sectional household survey suitable for country-wide data collection for immunization coverage at one point in time. The study was conducted in Uganda, with an estimated population of approximately 46 million people as of 2024 (8). In Uganda, immunization services are organized and provided under the Uganda National Expanded Program on Immunization (UNEPI), an arm of the Ministry of Health, through a decentralized health system. Children receive vaccines through static (health facility-based) sites or outreaches organized by health workers in the communities.

We included 2,254 children aged 12–23 months in the survey who were expected to have received DPT1 according to Uganda’s national immunization schedule by the Ministry of Health. Eligible participants were children and their caregivers who had lived together for at least six months, with prioritization being given to primary caregivers, especially mothers. We excluded caregivers with mental illness.

We determined the sample size using the World Health Organization Vaccination Coverage Cluster Survey Reference Manual to allow regional-level estimates across 15 regions. A multistage cluster sampling design was applied, where one district per region was randomly selected (with Kampala purposively included).

The outcome was having received no dose of DPT1 (zero-dose) (Yes/No). Independent variables included child characteristics, caregiver socio-demographics, health facility factors, and behavioral and social drivers of vaccination. Data were collected through face-to-face interviews using a pre-tested electronic questionnaire adapted from the WHO manual. We cleaned and analyzed data in Stata 17 using sampling weights. We conducted weighted descriptive statistics, bivariable analysis, and multivariable logistic regression, with statistical significance set at p<0.05. We only included variables with p<0.2 into the multivariate analysis and subsequently using backward elimination approach. We obtained ethical approval from the Ministry of Health and the Centers for Disease Control and Prevention, and verbal informed consent was secured from participants.

Results

Descriptive epidemiology

A total of 2,254 children were evaluated through their caregivers. Most 53% (1,152) of children were aged 12–17 months, with a median age of 17 months, with females being slightly more 52% (1,152) than males. Most caregivers were aged 25–39 years, 58% (1,237), with a median age of 28 years. Caregivers were mostly female, 95% (2,107), and were living in rural areas, 68% (1,819)

Prevalence of Zero-dose status among children aged 12–23 months in Uganda, August to September, 2024 by region

Among children aged 12–23 months in Uganda, the national prevalence of zero-dose status was 9.1%. The highest prevalence was from Bunyoro (17%) and South Central (17%), followed by Tooro (12%) and Busoga (12%) regions. The lowest prevalence was from Acholi (4%) and Kigezi (2%).

Factors associated with Zero-dose status among children aged 12–23 months in Uganda, 2024
In multivariable analysis, children aged 18–23 months had significantly lower odds of being zero-dose, with an 80% reduction compared to children aged 12–17 months. Caregivers with education above secondary level had significantly about seven times more odds of having a zero-dose child than others.  Lack of information about the next vaccination appointment had 18 times higher odds of having a zero-dose child compared to having information. Furthermore, distrust in vaccine-related information was associated with 7 times higher odds of zero-dose status compared to those who trusted vaccine information. Unfavorable family support was also significantly associated with zero-dose status, with 3.5 times higher odds among caregivers with support compared to those without (Table 1).   

Table 1: Factors associated with Zero-dose among children aged 12–23 months in Uganda, August to September, 2024

Variable	Zero-dose (%)
	Yes	No	cOR(95%CI)	aOR(95%CI)
Age of the child
12-17 months	13	87	Ref
18-23 months	4	96	0.29(0.19–0.45)	0.20(0.12–0.32)
Education of the caregiver
No education	9.5	90.5	Ref
Primary	11	89	1.1(0.63–2.1)	2.2(0.83–5.6)
Secondary	6	94	0.62(0.3–1.3)	1.6(0.56–4.4)
Above secondary	8	92	0.80(0.26–2.5)	6.6(1.5–28)
Relationship to child
Mother	8	92	Ref
Father	10	90	1.30(0.6–2.8)	0.8(0.34–1.9)
Grandparent	26	74	4(2.4–6.7)	3.8(1.8–8.3)
Other	24	76	3.7(0.91–15)	2.6 (0.52–13)
Next appointment information
Yes	7	93	Ref
No	53	47	16.(9.6–26)	18(8.5–38)
Trust in vaccines
Yes	1	99	Ref
No	9	91	12(3.6–37)	7.1(1.5–34)
Favorable family norms
Yes	7.98	92.02	Ref
No	25	75	3.9(2.2–6.9)	3.5(1.7–6.9)

 Discussion

The study found a national prevalence of zero-dose to be 9.1% and factors associated with zero-dose status to be lack of appointment information, distrust in vaccine information, having education above secondary level, and unfavourable family support. We found a national prevalence of zero-dose status at 9.1%, which is relatively low compared to that found in a study in Nigeria, which reported a zero-dose prevalence of 24% in 2021 (9), and a multi-country analysis by WHO and UNICEF in 2022 that found zero-dose exceeding 10% in several sub-Saharan African countries (10). The prevalence of zero-dose status in this study was lower than that in a study done in Togo by Mangbassim et al., reporting 27% among children aged 12-23 months (11). The comparatively lower prevalence in Uganda may be attributed to the country’s longstanding Uganda National Expanded Program on Immunization (UNEPI), supported by government and development partners through strategies such as Reaching Every District (RED) and Reaching Every Child (REC) approaches (12). This prevalence is higher than the national DPT1 prevalence reported in the 2022 Uganda Demographic and Health Survey (UDHS), which indicated missed DPT1 of approximately 4% (13).

The findings in this study are consistent with those by Wiysonge et al, who found that non-receipt of DPT1 was associated with maternal education, rural residence, and limited access to health services in sub-Saharan Africa (6). The findings in this study were in line with those from a study conducted in Cameroon by Nchinjoh et al showed that younger children had higher odds of being unvaccinated compared to older ones(14). These findings are also in line with previous studies conducted in sub-Saharan Africa and globally. Furthermore, this study found that unfavorable family norms and competing caregiver responsibilities influence immunization status. These findings are consistent with research from India and Kenya, which showed that household decision-making dynamics and gender roles can hinder mothers from prioritizing or accessing health services for their children, especially in male-dominated or resource-limited households (15, 16).  The findings in this study were also consistent with those found in another study where uneducated mothers had a lower risk of having zero-dose children (17). These factors remain a growing challenge to the immunization programs in Africa.

Conclusion

We found a zero-dose prevalence of 9.1%, driven by a combination of socio-demographic, behavioral, and social factors. We recommend strengthening community engagement by leveraging VHTs and local leaders to create awareness about the importance of vaccination and conducting VHT-led outreaches. Creation of appointment-reminder systems through media platforms like barazas and radios. Promoting trust-building communication by use of immunization champions to build caregiver trust in vaccines. We also recommend addressing unsupportive family norms by encouraging families to support caregivers in vaccination of children, and celebrating positive societal practices on immunization are essential strategi es to reach and immunize zero-dose children in Uganda.

Conflict of interest

The authors declare no conflict of interest

Author contribution

PA participated in the conception, design, data collection, analysis, and interpretation of the survey and wrote the draft manuscript. SN, NM, VK, BBK, DK, DM, DM, IS, MK, PMT, IA, FN, EOO, EM, AMN, SPK, DM, LB, and YN reviewed the report and the drafts of the manuscript and made several improvements to it. BK, RM, and ARA reviewed the final manuscript to ensure. Authors read and approved the final draft.

Acknowledgements

We thank all mentors and supervisors from Uganda Expanded Program on Immunization (UNEPI) and the Reproductive and Child Health Division from the Ministry of Health, the Uganda Public Health Fellowship Program, the Infectious Diseases Institute (IDI), and Makerere University for their support during this study. We also acknowledge the US CDC for supporting the activities of the Uganda Public Health Fellowship Program, under which this work was conducted.

Copyrighting and licensing

All material in the Uganda Public Health Bulletin is in the public domain and may be used and printed without permission. However, citation as to source is appreciated. Any article can be reprinted or republished. If cited as a reprint, it should be referenced in the original form.

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