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Published on: August 22, 2012
Individual level determinants for not receiving immunization, receiving immunization with delay, and being severely
Dustin G Gibson1, Benard Ochieng2, Eunice W Kagucia1
1Johns Hopkins Bloomberg School of Public Health, Department of International Health, Baltimore, MD, United States.
Insights
High immunization coverage in Kenya is noted, but vaccine delays are common. Delayed initial pentavalent vaccine significantly increases the risk of missing future immunizations, highlighting the link between coverage and timeliness for child health.
Area of Science:
- Pediatrics
- Public Health
- Epidemiology
Background:
- Vaccination coverage and timeliness are crucial for identifying at-risk populations.
- Understanding these metrics informs targeted interventions and public health policies.
Purpose of the Study:
- To estimate vaccination coverage and delays in children aged 12-23 months in rural western Kenya.
- To identify risk factors associated with incomplete, delayed, or severe underimmunization.
Main Methods:
- Caregiver surveys with immunization booklet records were used to collect data.
- Log-binomial regression analysis identified risk factors for immunization delays and underimmunization.
- Delayed immunization was defined as vaccination received >4 weeks past the scheduled date.
Main Results:
- High coverage was observed for Pentavalent1 (99%), Pentavalent3 (94%), measles (83%), and fully immunized child (FIC) status (80%).
- Significant proportions experienced delays: Pentavalent1 (10%), Pentavalent3 (24%), and measles (29%).
- Delayed Pentavalent1 receipt strongly predicted non-receipt of Pentavalent3, measles vaccine, and failure to achieve FIC.
Conclusions:
- While overall immunization coverage is high in the study area, a substantial number of children experience vaccination delays.
- Delayed initial vaccination is a significant risk factor for subsequent missed immunizations, underscoring the interconnectedness of coverage and timeliness.
- Advanced maternal age was the only consistent risk factor across all models.
Background:
Estimating vaccination coverage and delays are important because these measures can identify at risk sub-populations who can be targeted with interventions and public health policies. This paper sought to determine estimates and risk factors for children in rural western Kenya who did not receive immunization, received immunization with delay, or were severely underimmunized.
Methods:
Caregivers of children aged 12-23 months old were surveyed for immunization history using written records from the immunization booklet. Risk factors for not receiving immunization, delayed immunization, and severe underimmunization were calculated using log-binomial regression. Children were categorized as delayed if a given immunization was received greater than four weeks from the age-appropriate scheduled date. Severely underimmunized children were those who were fully unvaccinated for more than 90 days and had three or more vaccines delayed or not given.
Results:
Immunization coverage for pentavalent1, pentavalent3, measles, and fully immunized child (FIC; BCG, three doses of polio, three doses of pentavalent, and measles vaccines) were 99%, 94%, 83%, and 80%, respectively. Approximately, 10%, 24%, and 29%, of children were delayed for pentavalent1, pentavalent3, and measles, respectively. Each model produced a unique combination of risk factors with only advanced maternal age as a risk factor common to all models. Children with delayed receipt of pentavalent1 were at risk for not receiving pentavalent3 (RR: 5.20; 95%CI 3.48, 7.77), measles vaccine (RR: 1.48; 95%CI 1.12, 1.95), and not achieving FIC (RR: 1.88; 95%CI 1.51, 2.34) compared with children who received pentavalent1 on time.
Conclusions:
Immunization coverage among 12-23 month old children was high, yet a substantial proportion of children were vaccinated with delay. Although vaccine coverage and timeliness are often conceptualized as separate measures, the finding that delayed pentavalent1 receipt was a strong risk factor for not receiving future immunizations indicates the two measures are intertwined.
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