Two-Dose Measles-Containing Vaccine (MCV1 and MCV2) Completion and Associated Factors Among Children Aged 24–59 Months in Soroti City, Uganda: A Cross-Sectional Study

Introduction

Measles is a highly contagious viral airborne disease caused by the morbillivirus, characterized by fever, cough, conjunctivitis, and a maculopapular rash, and remains one of the leading causes of vaccine-preventable childhood deaths worldwide.¹ The World Health Organization (WHO) estimates that measles accounted for approximately 128,000 deaths globally in 2021, predominantly among children under five years.² Measles is preventable through measles-containing vaccines (MCV), with two doses recommended at nine months (MCV1) and 15–18 months (MCV2), requiring at least 95% coverage for both doses to achieve herd immunity.^2,3

Globally, MCV1 coverage stagnated at approximately 83% and MCV2 at 74% as of 2022.² In sub-Saharan Africa, MCV1 coverage was 74% and MCV2 only 58% as of 2024, contributing to recurrent measles outbreaks.⁴ In Uganda, measles immunization is delivered as a combined measles-rubella (MR) vaccine rather than a measles-only formulation; the terms MCV1/MCV2, used globally to denote the first and second doses of any measles-containing vaccine, are therefore used interchangeably in this paper with Uganda’s locally administered MR1/MR2. MR1 was introduced into the national schedule in 1981, while MR2 was added only in 2022.⁵ By the third quarter of the financial year 2023/2024, MR1 coverage was 90% but MR2 coverage was only 28%, falling dramatically below the 95% herd immunity threshold.^5,6 This wide gap likely reflects, in part, the relative recency of the second-dose introduction: caregiver awareness of MR2 as a distinct, required dose, and health-system routines for scheduling and reminding caregivers about it, are still maturing barely three years after national rollout.

Immunization services in Soroti City, as in the rest of Uganda, are delivered through both static, facility-based sessions at fixed health units and periodic outreach services, mobile or satellite vaccination sessions conducted by health workers at community sites (such as trading centers, churches, or schools) located far from a fixed facility, to reduce geographic and transport barriers to access. In the Teso sub-region where Soroti City is located, basic vaccination coverage stands at 70%, below the 95% national target.⁷ Uganda continues to experience recurrent, geographically dispersed measles outbreaks despite rising national coverage: by April 2026, the Ministry of Health reported active outbreaks across 20 districts nationally, with 12 deaths recorded that year,⁸ and a multi-district causality analysis across 12 affected districts (July 2025–March 2026) attributed these outbreaks primarily to incomplete MR2 delivery, irregular outreach, and weak follow-up of children who missed vaccination.⁹ A school-associated outbreak investigated in Gomba District in 2025 similarly found that only 72% of children were vaccinated, with unvaccinated status strongly predicting infection.¹⁰ Soroti Regional Referral Hospital’s own surveillance unit recorded confirmed measles admissions in early 2025 (Soroti Regional Referral Hospital, Measles Surveillance Unit, unpublished data, 2025); while this facility-level record is not independently published and is cited here as unpublished institutional data rather than a retrievable source, it is consistent with the wider national pattern of recurrent outbreaks in under-vaccinated districts documented above, and underscores the continued public health relevance of closing the MR2 completion gap in this setting. While national and multi-district evidence on factors associated with measles vaccination completion is available, subnational evidence specific to Soroti City is lacking, despite this local pattern and persistent reports of low coverage.

Understanding and addressing the factors influencing MCV completion at the subnational level is therefore essential, as national averages may mask significant local disparities. This study examined candidate factors across four conceptual levels commonly used in sub-Saharan African immunization research: individual (child) characteristics reflecting biological and behavioural risk (eg, birth order, health status), household characteristics shaping caregiver capacity and decision-making (eg, education, occupation, income, ANC attendance), health-system characteristics determining service accessibility (eg, outreach availability), and community characteristics reflecting the sociocultural environment (eg, beliefs about vaccination).^11,12 This study aimed to determine the measles immunization completion rate and associated factors among children aged 24–59 months in Soroti City, to generate locally relevant evidence to guide city-level strategies and inform targeted interventions.

Materials and Methods

Results

Discussion

This study determined that the measles immunization completion rate among children aged 24–59 months in Soroti City was 76.6% (95% CI: 71.7–80.9%), which is substantially higher than Uganda’s national MR2 uptake of 28%⁶ but remains below the WHO-recommended 95% threshold required for herd immunity.² This comparison should be interpreted cautiously, as the national estimate refers to the 2023/2024 financial year and to children reached through routine reporting nationally, whereas the present study estimate refers to children aged 24–59 months surveyed in late 2025/early 2026 in a single urban city; differences in period, age group, and data source may all contribute to the gap between the two figures, independent of any true underlying difference in coverage. With this caveat, the study’s completion rate is broadly comparable to global MCV2 coverage of 74%² and to completion rates reported from Ethiopia (75%) and Gondar City, Ethiopia (75.68%).^13,14 The relatively higher completion rate in Soroti City compared to the national average may partly reflect the urban setting, where proximity to health facilities and immunization services is generally greater than in rural areas. Nonetheless, the remaining gap to the 95% target underscores a continued risk of measles outbreaks in the city.

Children of birth order three and above were significantly less likely to complete measles immunization (AOR = 0.37; 95% CI: 0.15–0.93; p = 0.034). This finding aligns with evidence from Ethiopia where children of birth order three and above had significantly higher measles vaccination dropout rates¹⁵ and from Kenya where higher birth order was associated with lower MCV coverage.¹⁶ A plausible, though not directly measured, explanation is caregiver fatigue and competing demands with successive children, whereby increased family size may reduce individual attention to each child’s vaccination schedule;¹⁷ this mechanism is consistent with, though not confirmed by, findings from Cameroon describing logistical and financial challenges families face in ensuring multiple children attend scheduled vaccination appointments.¹⁷ In practical terms, this association suggests that community health workers and outreach teams could proactively flag households with three or more children during registration or ANC contact and prioritize them for reminder-based follow-up, such as home visits or phone/SMS reminders timed to each child’s due dose, though the effectiveness of such targeted follow-up was not tested in this study.

Children of unemployed caregivers were significantly more likely to complete immunization (AOR = 2.88; 95% CI: 1.50–5.52; p = 0.002). This finding, while counterintuitive, is consistent with evidence from East Africa showing employed mothers were less likely to fully vaccinate their children compared to housewives,¹² and from Botswana where unemployed caregivers demonstrated higher vaccination completion rates.¹⁸ Time availability is a plausible mechanism, employed caregivers, particularly those without flexible working arrangements or paid leave, may be more likely to miss vaccination appointments than those with more flexible time for health-seeking activities,¹⁸ but this study did not directly measure caregivers’ working hours, leave entitlements, or specific workplace barriers, and the explanation should therefore be read as a hypothesis rather than a demonstrated mechanism. Residual confounding is also possible: unemployment in this setting may correlate with other unmeasured factors, such as differences in socioeconomic support networks, extended family caregiving arrangements, or the specific type and formality of employment, any of which could independently affect the time and priority available for immunization visits.

Household income showed a non-linear association with completion after adjustment: children in the middle income category (200,000–<500,000 UGX) had significantly lower odds of completion than those in the lowest income category (AOR = 0.30; 95% CI: 0.15–0.61; p = 0.001), whereas the highest income category (≥500,000 UGX) did not differ significantly from the lowest (AOR = 0.91; 95% CI: 0.36–2.30; p = 0.850). This non-monotonic pattern is not straightforward to interpret and was not hypothesized a priori; it may reflect residual confounding by unmeasured factors that do not vary linearly with income in this sample (for example, differences in occupation type or residence between the income groups), and should be treated as an exploratory finding requiring confirmation in future, larger studies rather than as an established relationship between income and completion.

ANC attendance showed a dose-response relationship with completion, though only the highest attendance category reached statistical significance after adjustment. Mothers attending more than six ANC visits were significantly more likely to complete their child’s measles immunization (AOR = 5.77; 95% CI: 1.86–17.93; p = 0.002). Mothers attending 3–6 visits also had higher odds of completion than those attending 0–2 visits, but this difference did not reach statistical significance after adjustment (AOR = 2.12; 95% CI: 0.89–5.09; p = 0.091), suggesting that the benefit of ANC contact for immunization completion may only become statistically detectable at higher attendance intensity in this sample. This pattern is broadly consistent with findings from Gondar, Ethiopia where four or more ANC visits was linked to increased MCV2 coverage,¹⁴ from Oromia Regional State, Ethiopia where ANC attendance was a significant predictor of MCV uptake,¹⁹ and from Brazil.²⁰ A plausible pathway, though not directly assessed here, is that repeated ANC contact facilitates immunization completion through caregiver education on the vaccination schedule, trust-building with healthcare providers, and continuity of health-seeking behaviour into the child’s own immunization visits.¹⁹

Availability of outreach immunization services remained a strong independent predictor of completion after adjustment for the other five variables (AOR = 3.82; 95% CI: 1.90–7.70; p < 0.001). This is consistent with evidence from Afar, Ethiopia where households not reached by health extension workers had higher measles vaccination dropout rates,¹⁵ and from Kasese, Uganda where inadequate transport for outreach events hindered vaccine uptake.²¹ Outreach services likely reduce geographic and financial barriers to vaccination, provide additional platforms for health education, and extend services to caregivers who are otherwise unable to access facility-based care because of time or distance constraints.¹⁸

Caregivers who agreed that measles vaccines given at health facilities are safe had substantially higher odds of their children completing immunization than those who did not (AOR = 16.27; 95% CI: 2.83–93.64; p = 0.002). As reported in Results, this estimate proved sensitive to the exclusion of a handful of influential observations and is best treated as indicating a strong positive direction of association rather than a precisely estimated effect size or confidence interval; a bias-reduced sensitivity analysis supported the same direction at a somewhat more conservative magnitude (OR approximately 12–13). This fragility reflects the small number of caregivers who did not perceive the vaccine as safe (n = 10 of 325) rather than a problem with the overall model, whose other five predictors were stable under the same sensitivity check. Nonetheless, the direction is consistent with a substantial body of evidence linking caregiver vaccine-safety perceptions to uptake and completion of childhood immunization more broadly, and underscores that concerns about vaccine safety, even among a small minority of caregivers, may meaningfully affect completion in this setting. Because this study is cross-sectional, these interpretations describe plausible associations rather than demonstrated causal pathways, and should be read accordingly.

Limitations

This study has several limitations. The cross-sectional design limits causal inference regarding temporal relationships between exposures and immunization completion; associations reported here should be interpreted as descriptive/associational rather than causal. The multi-stage cluster sampling design was not accounted for in the sample-size calculation (no design effect was applied) or in the regression analysis (standard, rather than cluster-robust, standard errors were used); this may have led to underestimated standard errors and overly narrow confidence intervals. Variables for the multivariable model were selected using bivariate significance at p < 0.05; all six variables meeting this threshold (birth order, caregiver occupation, household income, ANC attendance, outreach services, and vaccine safety perception) were entered into the final model together, but this remains a pragmatic rather than fully conceptually driven variable-selection strategy, and may still have excluded variables that are conceptually relevant despite a non-significant bivariate association. Multicollinearity, goodness-of-fit, discrimination, and influential observations were formally assessed (Results) and did not raise concerns about the model as a whole; however, the vaccine safety perception estimate specifically was found to be sensitive to a small number of influential observations, reflecting its small reference category (n = 10), and its confidence interval should be treated as approximate rather than precise, pending re-estimation with dedicated bias-reduced (Firth-type) logistic regression software. Given the high prevalence of the outcome (76.6%), the reported odds ratios may diverge appreciably from the corresponding prevalence ratios and should not be interpreted as approximating relative risk. Immunization status was, for children whose health cards were unavailable, based on caregiver recall; this may have introduced recall bias and non-differential or differential misclassification, and because recall is generally more likely to over-report than under-report vaccination, the true completion rate may be somewhat lower than the 76.6% reported here. The exclusion of children with a prior confirmed measles diagnosis, while intended to avoid confounding from altered vaccination recommendations after natural infection, could also have modestly affected the estimated completion rate if excluded children differed systematically from those retained. The non-linear association observed between household income and completion was not hypothesized a priori and warrants cautious interpretation, as discussed above. Additionally, findings are specific to the urban context of Soroti City and may not be generalizable to rural settings in Uganda, where health access, awareness, and cultural factors may differ significantly. Finally, comparisons made in this paper between the study’s completion estimate and national MR2 coverage figures should be interpreted with caution, as the two estimates differ in reference period, age groups, and data source, as noted above.

Conclusion

The measles immunization completion rate among children aged 24–59 months in Soroti City was 76.6%, notably higher than Uganda’s national MR2 uptake of 28% (with the caveat regarding comparability noted above) but below the WHO-recommended 95% herd immunity threshold. Birth order of three and above, employed caregiver occupation, middle household income, lower ANC attendance, absence of outreach services, and caregiver doubt about vaccine safety were independently associated with lower immunization completion in this cross-sectional sample. Because intervention effectiveness cannot be established from this design, the following are offered as programmatic implications suggested by the observed associations rather than as interventions demonstrated to improve completion: strengthening targeted outreach services, integrating immunization counselling into ANC contacts, addressing caregiver concerns about vaccine safety through targeted health education, and prioritizing households with multiple children for reminder-based follow-up. Any consideration of more flexible vaccination scheduling for employed caregivers would benefit from dedicated local data on caregivers’ working hours and workplace constraints before being adopted as a specific recommendation. The non-linear income association warrants confirmation in future studies before being translated into a specific programmatic recommendation.

Ethics Statement

Ethical approval was obtained from the Mbale Regional Referral Hospital Research Ethics Committee (MRRH-2025-96).

Disclosure

The authors report no conflicts of interest in this work.