Child Vaccination Timing, Intervals and Missed Opportunities in Pastoral and Semi-Pastoral Areas in Ethiopia

Most vaccines in the immunisation schedule require two or more doses to trigger adequate immune response; appropriate timing, proper interval between vaccine doses, and completion of all vaccine doses are important to attain optimal protection. This study, led by the CORE Group Polio Project (CGPP) in Ethiopia, sought to evaluate and identify factors associated with the timeliness of vaccine doses, to assess the interval between vaccine doses, and to identify missed opportunities among children aged 12 to 23 months.

The study was conducted in CGPP implementation woredas, which are pastoralist and semi-pastoralist communities located in Benishangul-Gumuz, Gambella, Oromia, Somali, and Southern Nations, Nationalities and Peoples' (SNEP) regions in July 2015.A cross-sectional descriptive study was conducted that employed the 30 by 10 modified World Health Organization (WHO) immunisation coverage cluster sampling technique. Considering pastoral and semi-pastoral areas, a total of 60 clusters with a sample of 600 children aged 12 to 23 months and mothers/caregivers were included. Data were collected using smartphones loaded with the Open Data Kit (ODK) system and exported to STATA 12.0 for data description and analysis.

Complete responses were obtained from 582 respondents, with 54.8% of the sample from pastoral areas. About 51% of the respondents were Muslim, 68% had no education, and 67% were aged 30 or above. More than one-fifth (21.9%) of children received at least one vaccine dose earlier than the recommended minimum age. Nearly half (47.7%) of children received at least one subsequent dose earlier than an interval of 4 weeks. The overall rate of missed opportunities was 42.7%, which was higher in pastoral (61.4%) compared to semi-pastoral areas (30.9%) (P <0.001). Children from pastoral areas had a higher rate of missed opportunities compared to children from semipastoral areas (odds ratio (OR)=4.05; 95% confidence interval (CI): 2.28-7.22); and children from mothers/caregivers aged 30 or above had a higher rate of missed opportunities than mothers aged under 30 (OR=1.89; 95% CI: 1.32-3.13). This study found no significant association between caregivers' characteristics - such as residence, education, religion, age and occupation - and validity of vaccine doses. This is at variance with the findings of other research studies.

This study identified high proportions of children who started vaccination earlier than the recommended age (later for the first dose of Oral Polio Vaccine, or OPV0). (Vaccine administration before the recommended starting age for scheduled doses can result in suboptimal immune response due to prematurity of the immune system.) In addition, multiple vaccine doses were administered before the minimum interval of 4 weeks. Children in pastoral areas have higher rate of missed opportunities. Studies from 45 (developing and industrialised) countries identified missed opportunities were mainly due to: the failure to administer simultaneously all vaccines for which a child was eligible; false contraindications; health workers' practices, including not opening a multi-dose vaccine vial for a small number of people to avoid vaccine wastage; and logistical problems.

Recommendations based on the findings include:

• Strong interpersonal communication between mothers and vaccination service providers to remind mothers of the timely receipt of vaccines;
• Social and behavioural change communication strategies to educate and engage mothers on the importance of appropriate commencement of vaccination and adhering to the recommended time intervals between doses;
• Regular supervision and periodic in-service training of vaccination service providers to enhance their understanding of the importance of timely vaccine commencement and the need to maintain prescribed intervals between consecutive doses;
• Communication with immunisation service providers to encourage them to maintain stocks of the required amount of vaccine doses and to administer all the recommended antigens to reduce missed vaccination opportunities; and
• Further research to understand the reasons behind the high numbers of missed vaccination opportunities, inappropriate vaccine commencement, and incorrect spacing of vaccines doses, as well as to assess the readiness of immunisation service providers.

Editor's note: This article is part of a special issue of the Ethiopian Journal of Health Development featuring CGPP Ethiopia reflections on endeavours to improve immunisation uptake in Ethiopia.