Background: Childhood vaccination is an important public health intervention but there is limited information on coverage, trends, and determinants of vaccination completion in Uganda at the regional level. We examined trends in regional vaccination coverage and established the determinants of vaccination completion among children aged 12-23 months in Uganda. Methods: We analyzed data from the women’s questionnaire for the 1995-2016 Uganda Demographic Health Survey (UDHS). Vaccine completion was defined as having received a dose of Bacillus-Calmette Guerin (BCG) vaccine; three doses of diphtheria, pertussis, and tetanus (DPT) vaccine; three doses of oral polio vaccine (OPV) (excluding OPV given at birth); and one dose of measles vaccine. We performed Chi-square tests to compare vaccination completion by socio-demographic factors stratified by 10 sub-regions: Eastern, East Central, Central 1, Central 2, Kampala, Karamoja, North, Western, West Nile, and Southwest. We performed logistic regression analysis for each of the regions to identify factors associated with vaccination completion at 5% level of statistical significance. Results: Overall vaccination completion was 48.6% (95%CI, 47.2, 50.1) and ranged from 17.3% in Central 1 to 65.9% in Southwest. Vaccination completion rates declined significantly by 10.4% (95% confidence interval (CI), − 16.1, − 4.6) between 1995 and 2000, and increased significantly by 10.0% (95% CI, 4.6, 15.4) between 2000 and 2006, and by 5.4% (95% CI, 0.2, 10.6) between 2006 and 2011. Maternal education (secondary or higher level), receipt of tetanus toxoid (TT) during pregnancy, and possession of a child health card were associated with vaccination completion across all the sub-regions. Other factors like place of residence, religious affiliation, household wealth, maternal age, childbirth order, size of child at birth, and place of delivery were associated with vaccination completion but differed between the 10 sub-regions. Conclusion: Besides considerable regional variations, the vaccination completion rate among children aged 12-23 months in Uganda remains suboptimal despite the availability of vaccines. Maternal education, receipt of TT, and possession of a child health card are associated with a higher likelihood of vaccination completion among children aged 12-23 months in all the regions of Uganda. Interventions to improve the utilization of vaccination services in Uganda should consider these factors.

In April 2015, Kamwenge District, western Uganda reported a measles outbreak. We investigated the outbreak to identify potential exposures that facilitated measles transmission, assess vaccine effectiveness (VE) and vaccination coverage (VC), and recommend prevention and control measures. For this investigation, a probable case was defined as onset of fever and generalized maculopapular rash, plus ≥1 of the following symptoms: Coryza, conjunctivitis, or cough. A confirmed case was defined as a probable case plus identification of measles-specific IgM in serum. For case-finding, we reviewed patients’ medical records and conducted in-home patient examination. In a case-control study, we compared exposures of case-patients and controls matched by age and village of residence. For children aged 9 m-5y, we estimated VC using the percent of children among the controls who had been vaccinated against measles, and calculated VE using the formula, VE = 1 - ORM-H, where ORM-H was the Mantel-Haenszel odds ratio associated with having a measles vaccination history. We identified 213 probable cases with onset between April and August, 2015. Of 23 blood specimens collected, 78% were positive for measles-specific IgM. Measles attack rate was highest in the youngest age-group, 0-5y (13/10,000), and decreased as age increased. The epidemic curve indicated sustained propagation in the community. Of the 50 case-patients and 200 controls, 42% of case-patients and 12% of controls visited health centers during their likely exposure period (ORM-H = 6.1; 95% CI = 2.7–14). Among children aged 9 m-5y, VE was estimated at 70% (95% CI: 24–88%), and VC at 75% (95% CI: 67–83%). Excessive crowding was observed at all health centers; no patient triage-system existed. The spread of measles during this outbreak was facilitated by patient mixing at crowded health centers, suboptimal VE and inadequate VC. We recommended emergency immunization campaign targeting children <5y in the affected sub-counties, as well as triaging and isolation of febrile or rash patients visiting health centers.

: In 2017, the Global Task Force for Cholera Control (GTFCC) set a goal to eliminate cholera from ≥ 20 countries and to reduce cholera deaths by 90% by 2030. Many countries have included oral cholera vaccine (OCV) in their cholera control plans. We felt that a simple, user-friendly monitoring tool would be useful to guide national progress toward cholera elimination. We reviewed cholera surveillance data of Uganda from 2015 to 2021 by date and district. We defined a district as having eliminated cholera if cholera was not reported in that district for at least 4 years. We prepared maps to show districts with cholera, districts that had eliminated it, and districts that had eliminated it but then “relapsed.” These maps were compared with districts where OCV was used and the hotspot map recommended by the GTFCC. Between 2018 and 2021, OCV was administered in 16 districts previously identified as hotspots. In 2018, cholera was reported during at least one of the four previous years from 36 of the 146 districts of Uganda. This number decreased to 18 districts by 2021. Cholera was deemed “eliminated” from four of these 18 districts but then “relapsed.” The cholera elimination scorecard effectively demonstrated national progress toward cholera elimination and identified districts where additional resources are needed to achieve elimination by 2030. Identification of the districts that have eliminated cholera and those that have relapsed will assist the national programs to focus on addressing the factors that result in elimination or relapse of cholera.

There are 13 globally recognized rubella virus genotypes of which only 2 (1E and 2B) have been detected recently. The largest percentage of all reported rubella virus sequences come from China and Japan with Africa reporting limited data. In a bid to address the lack of rubella genotype data in Uganda and the World Health Organization Africa region, we sought to characterize rubella viruses retrospectively using sera collected from suspected measles patients that turned out rubella IgM positive. Seven sequences belonging to genotype 2B sub-lineage 2B-L2c were obtained. These sequences clustered with other genotype 2B sequences previously reported from Uganda. None of the other genotypes (1E and 1G) reported from Uganda in the earlier years were detected. In addition, none of the sequences were obtained after the introduction of the measles-rubella containing vaccine. The above highlight the need for continuous rubella virological surveillance to confirm interruption of endemic rubella genotype circulation.

Background: In Uganda, COVID-19-related disruptions increased the number of children who missed scheduled routine vaccination (defaulters). Identifying and following up with defaulter children is important for improving vaccination coverage. This paper describes Uganda’s experience in revitalizing community-led defaulter tracking to improve vaccination coverage post-COVID-19 in four purposefully selected districts. Methods: During two 6-month periods in 2022 and 2024, healthcare workers (HCWs) worked with village health teams (VHTs) to review health facility-based immunization registers, identify and track defaulters aged 0 to 59 months. VHTs visited identified defaulters’ homes, reviewed vaccination histories and reminded caregivers to bring defaulters to immunization sites for catch-up vaccination. Results: Overall, 20,922 defaulters were identified by health register review; VHTs located 15,749 (75.3%) through household visits, of whom 3688 (23.4%) were verified as previously vaccinated based on their home-based vaccination records, leaving 12,061 as true defaulters. Among the true defaulters, 9662 (80.1%) received at least one catch-up vaccination after follow-up by the VHT. The most frequently administered catch-up vaccines were measles–rubella first dose (MR1) at 55.4%, followed by diphtheria–tetanus–pertussis third dose (DTP3) at 48.3% and Bacillus Calmette–Guérin (BCG) at 47.4%. Among the 2399 children who remained unvaccinated after follow-up, the most common reasons were relocation outside the original catchment area (49.5%) and caregiver intention to vaccinate later (16.3%). Conclusion: Community-led defaulter tracking was feasible and improved vaccination uptake in post-COVID-19 Uganda. Strengthening the quality and availability of health facility immunization data, along with targeted community engagement, caregiver reminders and integrated vaccination services would improve identification and follow-up of defaulters, reducing population immunity gaps.

Background: Yellow fever vaccine stocks have been insufficient to cover exceptional demands for outbreak response. Fractional dosing evidence is limited to the 17DD substrain vaccine. We assessed the immunogenicity and safety of one-fifth fractional dose compared to standard dose of each of the four WHO-prequalified yellow fever vaccines produced from three substrains. Methods: We conducted a randomized, double-blind, non-inferiority trial in Mbarara, Uganda and Kilifi, Kenya. 960 participants aged 18-59 years without previous yellow fever vaccination or infection were recruited from communities and randomized to receive one of four vaccines and to standard or fractional dosage. Vaccine was administered subcutaneously by unblinded nurse. Other study personnel and participants were blinded to vaccine allocation. Primary immunogenicity outcome, seroconversion, was measured in the per-protocol population; safety outcomes included all vaccinated participants. We defined non-inferiority as no more than 10% decrease in seroconversion in fractional compared to standard dose arms 28 days post-vaccination. Seroconversion was defined as ≥4-fold rise in neutralizing antibody titers measured by 50% plaque reduction neutralization test (PRNT ₅₀ ). ClinicalTrials.gov Identifier: NCT02991495 , following participants. Findings: Between 6 ^th November 2017 and 21 ^st February 2018, 960 participants, total sample goal, were randomized. The primary per-protocol analysis includes 899 participants, with 110 to 117 participants per arm. The absolute difference in seroconversion between fractional and standard doses by vaccine was 1.71% (95%CI: −2.60, 5.28), −0.90% (95%CI: −4.24, 3.13), 1.82% (95%CI: −2.75, 5.39), 0.0% (95%CI: −3.32, 3.29). Fractional doses from all four vaccines met the non-inferiority criterion. There were no safety concerns. Interpretation: These results support fractional dosing of all WHO-prequalified yellow fever vaccines for the general adult population for outbreak response in situations of vaccine shortage. Funding: The study was funded by Médecins Sans Frontières Foundation, Wellcome Trust (grant no. 092654) and the UK Department for International Development. Vaccines were donated in kind. Research in context: Evidence before this study: In July 2016, following major yellow fever (YF) outbreaks in two countries, WHO published a secretariat information paper including a review of studies assessing the immunogenicity of fractional doses of YF vaccines and recommended consideration of fractional doses to manage a vaccine shortage. Following this, fractional doses of YF vaccine produced by Bio-Manguinhos/Fiocruz (17DD substrain) were given to approximately 7.5 million non-pregnant adults and children ≥ 2 years of age in Kinshasa, Democratic Republic of Congo. The evidence base to support this action was limited to a single vaccine substrain and to a specific context. To broaden and simplify recommendations, WHO called for additional research to be conducted. We designed a trial to assess non-inferiority in seroconversion of fractional (one-fifth dose) versus standard dose for each of the four WHO-prequalified YF vaccines at 28 days post-vaccination in an adult population in Kenya and Uganda. We selected vaccine batches as close as possible to each manufacturer’s minimum release specification. Added value of this study: This is the first randomized controlled trial assessing all four WHO-prequalified YF vaccines, providing information on the immunogenicity and safety of fractional doses of the different vaccine substrains at 10 days, 28 days and one year post-vaccination. The results show that, at 28 days post-vaccination, most participants had high levels of neutralizing antibodies and that seroconversion rates in the fractional dose arms were non-inferior to standard dose for each of the four vaccines. Seroconversion rates and neutralizing antibodies remained high up to one year post-vaccination for both fractional and standard doses for all vaccines. These results are aligned with previous studies using the 17DD substrain vaccine but extend the evidence to randomized comparisons of all four vaccines and to a sub-Saharan Africa context. To our knowledge, this is the first trial assessing immunogenicity of fractional doses at 10 days post-vaccination. Implications of all the available evidence: Our study supports the use of one-fifth fractional doses of all four WHO-prequalified yellow fever vaccines for the general adult population and fills a critical knowledge gap to support WHO policy on the use of fractional dosing of yellow fever vaccine for outbreak response. The immunogenicity and safety of fractional dosing in children and specific populations, such as those living with HIV, is yet to be determined. Long-term studies are warranted to confirm the duration of protection.