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Vaccine Delay and Its Association With Undervaccination in Children in Sub-Saharan Africa
Cara Bess Janusz1, Margaret Frye2, Martin K Mutua3
1Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, Michigan; The Global Institute for Vaccine Equity, University of Michigan, Ann Arbor, Michigan.
Insights
Delayed childhood vaccinations in Sub-Saharan Africa are common, particularly for measles vaccines. Timely vaccination is crucial for completing immunization schedules and reducing child mortality.
Area of Science:
- Global Health
- Pediatrics
- Vaccinology
Background:
- Improving vaccination timeliness and completion is critical for reducing under-5 childhood mortality in Sub-Saharan Africa.
- Delayed vaccination poses a significant risk to infant health and program effectiveness.
Purpose of the Study:
- To assess the prevalence of delayed vaccinations for key infant doses (birth, 6, 10, 14 weeks, 9 months).
- To examine the association between dose-specific vaccination delays and undervaccination among infants in Sub-Saharan Africa.
Main Methods:
- Data from 33 Sub-Saharan African countries (2010-2019 Demographic and Health Surveys) were analyzed.
- Vaccination timing and series completion were assessed for children aged 12-35 months.
- Logistic regression modeled the association between vaccination delays and incomplete immunization schedules.
Main Results:
- High proportions of children experienced delays: 25.9% for Bacille Calmette-Guerin (birth), 49.1% for pentavalent vaccine (14 weeks), and 63.9% for measles (9 months).
- Delayed vaccination was significantly associated with lower maternal education and wealth.
- Vaccination delays strongly predicted incomplete immunization schedules (e.g., AOR=3.76 for measles).
Conclusions:
- Timely vaccination initiation is linked to higher immunization schedule completion rates.
- Improving vaccination timeliness can enhance the impact of immunization programs on child health in Sub-Saharan Africa.
Introduction:
Improving the timeliness and completion of vaccination is the key to reducing under-5 childhood mortality. This study examines the prevalence of delayed vaccination for doses administered at birth and age 6 weeks, 10 weeks, 14 weeks, and 9 months and its association with undervaccination among infants in Sub-Saharan Africa.
Methods:
Pooling data across 33 Sub-Saharan Africa countries, vaccination timing and series completion were assessed for children aged 12-35 months who were included in the immunization module of the Demographic and Health Surveys conducted between 2010 and 2019. Survey design-adjusted logistic regression modeled the likelihood of not fully completing the basic immunization schedule associated with dose-specific delays in vaccination. Data were obtained and analyzed in May 2020.
Results:
Among children with complete date records (n=70,006), the proportion of children vaccinated with delays by ≥1 month was high: 25.9% for Bacille Calmette-Guerin (at birth); 49.1% for the third dose of pentavalent combination vaccine (at 14 weeks); and 63.9% for the first dose of measles vaccines (at 9 months). Late vaccination was more common for children born to mothers with lower levels of educational attainment (p<0.001) and wealth (p<0.001). Controlling for place, time, and sociodemographics, vaccination delays at any dose were significantly associated with not completing the immunization schedule by 12 months (Bacille Calmette-Guerin: AOR=1.93, [95% CI=1.83, 2.02]; pentavalent 3: AOR=1.50 [95% CI=1.35, 1.64]; measles: AOR=3.76 [95% CI=3.37, 4.15]).
Conclusions:
Timely initiation of vaccination could contribute to higher rates of immunization schedule completion, improving the reach and impact of vaccination programs on child health outcomes in Sub-Saharan Africa.
Supplement Information:
This article is part of a supplement entitled Global Vaccination Equity, which is sponsored by the Global Institute for Vaccine Equity at the University of Michigan School of Public Health.
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