Effects of three interventions and determinants of full vaccination among children aged 12-59 months in Nyanza province, Kenya

The role of community health and nutrition volunteers in improving the health and nutrition status of infant and young children in remote areas, Hajjah, Yemen

BACKGROUND

In Yemen, morbidity and malnutrition are major public health problems. The Community Health and Nutrition Volunteers (CHNVs) program was launched to tackle these problems through providing services to mothers and their children residing in remote villages. Since establishment of the CHNVs program in Yemen, its outcome has never been evaluated. Therefore, the aim of this study was to assess the role of CHNVs in improving the immunization, morbidity and nutritional status of infant and young children (IYC).

METHODS

A comparative cross-sectional study design was conducted in Al-Maghrabah and Bani-Qais districts, Hajjah governorate. It was carried out between January and April 2023. A three-stage cluster sampling method was used. A total of 926 IYC with their mothers were interviewed using a pre-tested questionnaire. SPSS 26 was used for data analysis. The multinomial logistic regression and chi-square or fisher exact tests were used to compare the vaccination, morbidity and nutritional status of IYC between the volunteer and non-volunteer villages. Odds Ratio (OR) with 95% Confidence Interval (CI) were calculated. A p value < 0.05 was considered statistically significant.

RESULTS

The IYC in volunteer villages were more likely to be fully or partially vaccinated compared to those in non-volunteer villages [OR = 2.3, 95% CI: 1.5-3.7, p < 0.0001, and OR = 1.9, 95% CI: 1.3-2.8, p = 0.001, respectively]. The specific coverage rates for BCG, and the 1st and 2nd doses of OPV/Pentavalent/Pneumo/Rota vaccines were significantly higher in the volunteer compared to non-volunteer villages [(OR = 1.8, 95% CI: 1.3-2.5, p < 0.0001), (OR = 1.5, 95% CI: 1.2-2.1, p = 0.003), and (OR = 1.5, 95% CI: 1.2-2.0, p = 0.002), respectively]. Moreover, the prevalence of diarrhea and fever among IYC was significantly lower in the volunteer compared to non-volunteer villages [(OR = 0.7, 95% CI: 0.5-0.9, p = 0.004) and (OR = 0.7 95% CI: 0.5-0.9, p = 0.045), respectively].

CONCLUSIONS

The study found that CHNVs play a significant role in improving vaccination status and the coverage rate for BCG, and 1st and 2nd doses of OPV/Pentavalent/Pneumo/Rota vaccines, and reducing the prevalence of diarrhea and fever among IYC in their villages compared to non-volunteer villages, in Hajjah governorate. Future follow-up study and expansion to other settings in different governorates is recommended.

Pentavalent vaccination in Kenya: coverage and geographical accessibility to health facilities using data from a community demographic and health surveillance system in Kilifi County

Background

There is substantial evidence that immunization is one of the most significant and cost-effective pillars of preventive and promotive health interventions. Effective childhood immunization coverage is thus essential in stemming persistent childhood illnesses. The third dose of pentavalent vaccine for children is an important indicator for assessing performance of the immunisation programme because it mirrors the completeness of a child’s immunisation schedule. Spatial access to an immunizing health facility, especially in sub-Sahara African (SSA) countries, is a significant determinant of Pentavalent 3 vaccination coverage, as the vaccine is mainly administered during routine immunisation schedules at health facilities. Rural areas and densely populated informal settlements are most affected by poor access to healthcare services. We therefore sought to determine vaccination coverage of Pentavalent 3, estimate the travel time to health facilities offering immunisation services, and explore its effect on immunisation coverage in one of the predominantly rural counties on the coast of Kenya.

Methods

We used longitudinal survey data from the health demographic surveillance system implemented in Kaloleni and Rabai Sub-counties in Kenya. To compute the geographical accessibility, we used coordinates of health facilities offering immunisation services, information on land cover, digital elevation models, and road networks of the study area. We then fitted a hierarchical Bayesian multivariable model to explore the effect of travel time on pentavalent vaccine coverage adjusting for confounding factors identified a priori.

Results

Overall coverage of pentavalent vaccine was at 77.3%. The median travel time to a health facility was 41 min (IQR = 18–65) and a total of 1266 (28.5%) children lived more than one-hour of travel-time to a health facility. Geographical access to health facilities significantly affected pentavalent vaccination coverage, with travel times of more than one hour being significantly associated with reduced odds of vaccination (AOR = 0.84 (95% CI 0.74 – 0.94).

Conclusion

Increased travel time significantly affects immunization in this rural community. Improving road networks, establishing new health centres and/or stepping up health outreach activities that include vaccinations in hard-to-reach areas within the county could improve immunisation coverage. These data may be useful in guiding the local department of health on appropriate location of planned immunization centres.

Community health workers and health equity in low- and middle-income countries: systematic review and recommendations for policy and practice

Background

The deployment of Community Health Workers (CHWs) is widely promoted as a strategy for reducing health inequities in low- and middle-income countries (LMIC). Yet there is limited evidence on whether and how CHW programmes achieve this. This systematic review aimed to synthesise research findings on the following questions: (1) How effective are CHW interventions at reaching the most disadvantaged groups in LMIC contexts? and (2) What evidence exists on whether and how these programmes reduce health inequities in the populations they serve?

Methods

We searched six academic databases for recent (2014–2020) studies reporting on CHW programme access, utilisation, quality, and effects on health outcomes/behaviours in relation to potential stratifiers of health opportunities and outcomes (e.g., gender, socioeconomic status, place of residence). Quantitative data were extracted, tabulated, and subjected to meta-analysis where appropriate. Qualitative findings were synthesised using thematic analysis.

Results

One hundred sixty-seven studies met the search criteria, reporting on CHW interventions in 33 LMIC. Quantitative synthesis showed that CHW programmes successfully reach many (although not all) marginalized groups, but that health inequalities often persist in the populations they serve. Qualitative findings suggest that disadvantaged groups experienced barriers to taking up CHW health advice and referrals and point to a range of strategies for improving the reach and impact of CHW programmes in these groups. Ensuring fair working conditions for CHWs and expanding opportunities for advocacy were also revealed as being important for bridging health equity gaps.

Conclusion

In order to optimise the equity impacts of CHW programmes, we need to move beyond seeing CHWs as a temporary sticking plaster, and instead build meaningful partnerships between CHWs, communities and policy-makers to confront and address the underlying structures of inequity.

Trial registration

PROSPERO registration number CRD42020177333.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12939-021-01615-y.

Preventive Health Service Coverage Among Infants and Children at Six Maternal-Child Health Clinics in Western Kenya: A Cross-Sectional Assessment

OBJECTIVES

Despite the substantial reduction of child mortality in recent decades, Kenya still strives to provide universal healthcare access and to meet other international benchmarks for child health. This study aimed to describe child health service coverage among children visiting six maternal and child health (MCH) clinics in western Kenya.

METHODS

In a cross-sectional study of Kenyan children who are under the age of 5 years presenting to MCH clinics, child health records were reviewed to determine coverage of immunizations, growth monitoring, vitamin A supplementation, and deworming. Among 78 children and their caregivers, nearly 70% of children were fully vaccinated for their age.

RESULTS

We found a significant disparity in full vaccination coverage by gender (p = 0.017), as males had 3.5 × higher odds of being fully vaccinated compared to females. Further, full vaccination coverage also varied across MCH clinic sites ranging from 43.8 to 92.9%.

CONCLUSIONS FOR PRACTICE

Health service coverage for Kenyan children in this study is consistent with national and sub-national findings; however, our study found a significant gender equity gap in coverage at these six clinics that warrants further investigation to ensure that all children receive critical preventative services.

Understanding the complexity of demand-side determinants on vaccine uptake in sub-Saharan Africa

Routine vaccination annually prevents millions of deaths worldwide but is underutilized in sub-Saharan Africa (SSA). The complexity of socio-cultural factors impacting vaccine uptake is not well understood. Hence, this paper aims to review the socio-cultural determinants of vaccine uptake and visualize their interrelationships. We conducted a literature search using Pubmed and Embase databases, including articles published from 2000 to 2019 describing socio-cultural demand-side determinants for vaccine uptake. Using the Andersen and Newman Framework of Health Services Utilization, demand-side determinants were categorized as predisposing, enabling or need factors. A qualitative system dynamics approach was employed to visualize how these factors and their dynamic interrelationships influence vaccine uptake. This visualization, by means of a causal-loop diagram (CLD), was mostly based on a qualitative input, with the majority being statements of the authors. These statements were abstracted from the papers found in the review. Quantification was done by counting direct (statistical) associations between each determinant and 'timely and full routine immunization coverage'. A total of 90 articles, primarily from Nigeria (n = 23), Ethiopia (n = 17) and Kenya (n = 11), met the inclusion criteria. We find that maternal autonomy and the perceived benefits caregivers attach to vaccination and exert their influences on many other factors through several feedback loops, thereby influencing timely and full routine immunization coverage. Utilization of health services (supply-related) and access to information (demand-related) were considered as high-potential leverage points. Quantification has shown that maternal autonomy and perceived benefit have an unclear evidence base. Future research should focus on these key players as they play a central role in multiple complex pathways, through which they could influence the uptake of vaccines in SSA.

Bayesian Analysis of Predictors of Incomplete Vaccination against Polio among Children Aged 12-23 Months in Ethiopia

Background: The re-introduction of polio among children aged 12–23 months is likely to occur in Ethiopia due to the low vaccination rates against poliovirus. The study sought to examine the predictors of incomplete vaccination against polio among children aged 12–23 months in Ethiopia. Methods: The data used were obtained from the 2016 Ethiopia Demographic and Health Survey. Binary and Bayesian logistic regressions were used for the data analysis, with parameters estimated using classical maximum likelihood and the Bayesian estimation method. Results: The results revealed that 43.7% of the children were not fully vaccinated against polio in Ethiopia. Maternal age, educational level, household wealth index, exposure to mass media, place of residence, presence of nearby healthy facility, counseling on vaccination, and place of delivery were significant determinants of incomplete polio vaccination among children aged between 12 and 23 months in Ethiopia. Conclusion: Considerable numbers of children are not fully vaccinated against polio in Ethiopia. Individual and contextual factors significantly contributed to incomplete polio vaccination among children in the country. Therefore, the government and other stakeholders should pay particular attention to maternal education to increase mothers’ educational level in all regions and give training and counseling in all urban and rural parts of the country on child vaccination to overcome the problem of children’s incomplete polio vaccination and/or vaccination dropout.

Inequalities in Access and Utilization of Maternal, Newborn and Child Health Services in sub-Saharan Africa: A Special Focus on Urban Settings

OBJECTIVES

The aim of this paper is to share the results of a systematic review on the state of inequalities in access to and utilization of maternal, newborn and child health (MNCH) services in the sub-Saharan African region. The focus of the review was on urban settings where growing needs and challenges have been registered over the past few years due to rapid increase in urban populations and urban slums.

METHODS

The review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Studies published in English between 2000 and 2019 were included. A narrative synthesis of both qualitative and quantitative data was undertaken. The record for registration in PROSPERO was CRD42019122066.

RESULTS

The review highlights a great variation in MNCH services utilization across urban sub-Saharan Africa (SSA). The main aspects of vulnerability to unequal and poor MNCH services utilization in urban settings of the region include poverty, low level of education, unemployment, lower socioeconomic status and poor livelihoods, younger maternal age, low social integration and social support, socio-cultural taboos, residing in slums, and being displaced, refugee, or migrant. At the health system level, persistent inequalities are associated with distance to health facility, availability of quality services and discriminating attitudes from health care personnel.

CONCLUSION

Context-specific intervention programs that aim at resolving the identified barriers to access and use MNCH services, particularly for the most vulnerable segments of urban populations, are essential to improve the overall health of the region and universal health coverage (UHC) targets.

Rapidly modifiable factors associated with full vaccination status among children in Niamey, Niger: A cross-sectional, random cluster household survey

Background and objectives

Vaccination status becomes more equitable when interventions are carried out to eliminate poverty or to improve levels in maternal education. Low-income countries need to identify interventions that would have a more immediate and equitable effect. The present study aimed to identify rapidly modifiable factors associated with full vaccination status among children in Niamey, Niger.

Methods

A cross-sectional, random cluster household survey was conducted in Niamey’s five health districts. Data on vaccination coverage and socioeconomic household characteristics were collected. Logistic regression analysis was conducted with data on 445 mothers and their children aged 12–23 months.

Results

Of 445 children, 38% were fully vaccinated. Mothers who were satisfied with their health worker’s attitude and had correct vaccination calendar knowledge (adjusted odds ratio [aOR] 5.32, 95% confidence interval [CI] 2.05–13.82) were more likely to have fully vaccinated children. Mothers who had completed secondary school (aOR 2.04, 95% CI 1.17–3.55) were also associated with having fully vaccinated children.

Conclusions

A higher rate of full vaccination among children could be achieved by relatively short-term modifiable factors. These modifiable factors are mothers’ satisfaction with health workers’ attitudes and knowledge of the vaccination calendar. Maternal satisfaction with health workers’ attitudes could be improved through better interpersonal communication between health workers and mothers. Specifically, mothers should be given specific information on time intervals between appointments. Strengthened communication interventions may be effective in improving both the acceptability of health services and low vaccination coverage.

Characterization of immunization secondary analyses using demographic and health surveys (DHS) and multiple indicator cluster surveys (MICS), 2006-2018

BACKGROUND

Infant immunization coverage worldwide has plateaued at about 85%. Using existing survey data to conduct analyses beyond estimating coverage may help immunization programmes better tailor strategies to reach un- and under-immunized children. The Demographic and Health Survey (DHS) and the Multiple Indicators Cluster Survey (MICS), routinely conducted in low and middle-income countries (LMICs), collect immunization data, yet vaccination coverage is often the only indicator reported and used. We conducted a review of published immunization-related analyses to characterize and quantify immunization secondary analyses done using DHS and MICS databases.

METHODS

We conducted a systematic search of the literature, of immunization-related secondary analyses from DHS or MICS published between 2006 and August 2018. We searched 15 electronic databases without language restrictions. For the articles included, relevant information was extracted and analyzed to summarize the characteristics of immunization-related secondary analyses. Results are presented following the PRISMA guidelines.

RESULTS

Among 1411 papers identified, 115 met our eligibility criteria; additionally, one article was supplemented by the Pan American Health Organization. The majority were published since 2012 (77.6%), and most (68.9%) had a first or corresponding author affiliated with institutions in high-income countries (as opposed to LMICs where these surveys are conducted). The median delay between survey implementation and publication of the secondary analysis was 5.4 years, with papers with authors affiliated to institutions in LMIC having a longer median publication delay (p < 0.001). Over 80% of the published analyses looked at factors associated with a specific vaccine or with full immunization. Quality proxies, such as reporting percent of immunization data from cards vs recall; occurrence and handling of missing data; whether survey analyses were weighted; and listing of potential biases or limitations of the original survey or analyses, were infrequently mentioned.

CONCLUSION

Our review suggests that more needs to be done to increase the increase the utilization of existing DHS and MICS datasets and improve the quality of the analyses to inform immunization programmes. This would include increasing the proportion of analyses done in LMICs, reducing the time lag between survey implementation and publication of additional analyses, and including more qualitative information about the survey in the publications to better interpret the results.

Trends, Spatial Disparities, and Social Determinants of DTP3 Immunization Status in Indonesia 2004-2016

Although 91% of 12-23-month-old children in Indonesia received at least one immunization in 2013, only 76% completed DTP3 immunization. This percentage is below the UNICEF and WHO recommended standards. Thus, this study aims to investigate trends, spatial disparities, and social determinants related to low coverage of DTP3 immunization in Indonesia. Using a multilevel approach, we analyzed data from 305,090 12-23-month-old children living across approximately 500 districts in Indonesia to study demand and supply factors determining DTP3 immunization status. We examined unique, nationally representative data from the National Socioeconomic Survey (Survei Sosial Ekonomi Nasional or Susenas) and Village Potential Census (Potensi Desa or Podes) from 2004 to 2016. The percentage of children receiving complete DTP3 immunization increased from 37.8% in 2004 to 75.9% in 2016. Primarily income, parity status, and education, showed influence on DTP3 coverage. Among individual-level factors, the presence of a professional birth attendant was the most influential factor. At the district level, the factors varied. Low progress in DTP3 immunization status in Indonesia is due to huge disparities across the country's islands, in the density of health services, and in household socioeconomic status.

Determinants of timeliness in early childhood vaccination among mothers with vaccination cards in Sindh province, Pakistan: a secondary analysis of cross-sectional survey data

OBJECTIVE

Untimely vaccination refers to receiving the given dose before (early) or after (delayed) the recommended time window. The purpose of this study was to assess the extent of timeliness of childhood vaccinations and examine the determinants of vaccination timeliness in Sindh province, Pakistan.

DESIGN

Cross-sectional analysis of data from the 2013 and 2014 Maternal and Child Health Program Indicator Surveys.

SETTING

Community-based maternal and child health surveys.

PARTICIPANTS

Among 10 200 respondents of Maternal and Child Health Program Indicator Surveys, 1143 women who had a live birth in the 2 years preceding the survey were included.

OUTCOMES

At the participants' home, an interviewer asked mothers to show their children's vaccination cards, which contained information regarding vaccinations. Children's vaccination status was categorised into timely or early/delayed compared with vaccination schedule. A logistic regression analysis using Firth's penalised likelihood was performed to identify factors associated with timeliness of vaccinations.

RESULTS

238 children (20.8% of children who received a full set of basic vaccinations) received all vaccinations on schedule among children who received a full set of basic vaccinations. The percentages of timely vaccinations ranged from 2.3% for second measles vaccination to 89.3% for bacillus Calmette-Guérin. Child's age and place of delivery were associated with timely vaccinations. Older child age and institutional delivery were associated with decreased timely vaccination rate.

CONCLUSIONS

Home-based vaccination record is a key tool to improve the timeliness of vaccinations. The redesigned vaccination cards, the new electronic registries for vaccination card information and the vaccination tracking system to remind the second/third vaccination visits may be helpful to improve timely vaccinations for children under 2 years old.

Contribution of women's development army to maternal and child health in Ethiopia: a systematic review of evidence

OBJECTIVE

The aim of this review was to identify, appraise and synthesise studies that reported on the contribution of women's development army (WDA) to maternal and child health development.

SETTING

Studies conducted in Ethiopia 2010 onwards and published in English were considered.

DATA SOURCES

Evidence were searched in MEDLINE, CINAHL and EBSCOhost from 25 March to 10 April 2018.

ELIGIBILITY CRITERIA

Both quantitative and qualitative studies assessing the contribution of WDA to maternal and child health were considered.

DATA EXTRACTION AND SYNTHESIS

Two independent reviewers have extracted data using pre-planned data extraction tool separately for each study design. Findings were synthesised using tables and narrative summary.

OUTCOME

Maternal and child health services; maternal and child mortality.

RESULTS

Nine studies met the inclusion criteria and were used for synthesis. The results revealed that participation and membership in women's development teams (WDTs) have a positive effect on minimising maternal death and improving child immunisation service use. Skilled delivery and antenatal care service use were higher in WDTs located within a radius of 2 km from health facilities. Women's development teams were also the main sources of information for mothers to prepare themselves for birth and related complications. Moreover, well-established groups have strengthened the linkage of the health facility to the community so that delays in maternal health service use were minimised; health extension workers could effectively refer women to a health facility for birth and utilisation of skilled birth service was improved.

CONCLUSION

Voluntary health service intervention in Ethiopia has improved maternal and child health services' outcome. A decrease in maternal deaths, increase in antenatal and delivery service use and improved child immunisation service uptake are attributable to this intervention. The linkage between community members and the primary healthcare system served as an effective and efficient mechanism to share information.

Childhood vaccination in Kenya: socioeconomic determinants and disparities among the Somali ethnic community

OBJECTIVES

Kenya has a significant refugee population, including large numbers of Somali migrants. This study examines the vaccination status of Kenyan children and sociodemographic predictors of vaccination, including Somali ethnicity.

METHODS

Using the 2014 Kenyan Demographic and Health Survey, we calculated the proportion of non-vaccinated, under-vaccinated, and fully vaccinated children, defining full vaccination as one dose Bacille Calmette-Guerin, three doses polio, three doses pentavalent, and one dose measles. We assessed associations among various factors and vaccination status using multinomial logistic regression and explored the effect of Somali ethnicity through interaction analysis.

RESULTS

The study sample comprised 4052 children aged 12-23 months, with 79.4% fully, 19.0% under-, and 1.6% non-vaccinated. Among Somalis, 61.9% were fully, 28.7% under-, and 9.4% non-vaccinated. Somalis had significantly greater odds of under- and non-vaccination than the Kikuyu ethnic group. Wealth and birth setting were associated with immunization status for Somalis and non-Somalis.

CONCLUSIONS

Disparities persist in pediatric vaccinations in Kenya, with Somali children more likely than non-Somalis to be under-vaccinated. Health inequalities among migrants and ethnic communities in Kenya should be addressed.

Factors affecting complete and timely childhood immunization coverage in Sindh, Pakistan; A secondary analysis of cross-sectional survey data

BACKGROUND

Pakistan has a high burden of newborn mortality, which would be significantly preventable through appropriate routine immunization. The purpose of this study was to measure the basic timely childhood immunization coverage and to identify determinants of factors influencing childhood immunization coverage in Sindh, Pakistan.

METHODS

Data from Maternal and Child Health Program Indicator Survey 2013-2014 which was conducted in Sindh province of Pakistan was used. Outcome measure was full coverage of the basic immunization schedule from child's vaccination card. The association of receiving basic immunization with demographic factors, socioeconomic status, mother and child health information sources, and perinatal care factors were tested by binary logistic regression.

RESULTS

Among 2,253 children, 1,156 (51.3%) received age-based full basic immunization. The basic immunization rates were 69.1% for under five weeks old, 38.3% for six to nine weeks, 18.8% for 10-13 weeks, 44.0% for 14 weeks-eight months, 60.4% for nine to 11 months, and 59.1% for over one year. Child's age, number of living children, parents' education level, wealth, the source of mother and child health information, number of antenatal care, and assistance during delivery were associated with completing basic immunization.

CONCLUSIONS

The overall full basic immunization coverage in Pakistan was still low. Policy makers should identify children at risk of low immunization coverage and obstacles of receiving antenatal care, implement educational interventions targeting on less educated parents, and conduct mass immunization campaigns for timely and complete immunization.

Incomplete immunization among children aged 12-23 months in Togo: a multilevel analysis of individual and contextual factors

BACKGROUND

Inadequate immunization coverage remains a public health problem in Africa. In Togo, only 62% of children under one year of age were fully immunized in 2013. This study aimed to estimate the immunization coverage among children aged 12-23 months, and to identify factors associated with incomplete immunization status in Togo.

METHODS

A cross-sectional survey was conducted in the six health regions of Togo. Children aged 12 to 23 months who were living with one of their parents or guardians from selected households were recruited for the study. Data was collected using a pre-tested questionnaire through face-to-face interviews. Multilevel logistic regression analyses were performed to assess factors associated with incomplete immunization coverage.

RESULTS

A total of 1261 households were included. Respondents were predominantly women (91.9%) and 22.8% had secondary or higher education level. Immunization cards were available for 85.3% of children. Complete immunization coverage was 72.3%, 95% confidence interval (CI): [69.7-74.8]). After controlling for both individual and contextual level variables, children whose mothers attended secondary school or above were 33% (adjusted Odds Ratio (aOR) = 0.67, CI [0.47-0.94]) less likely to have an incomplete immunization coverage compared to those with no education. The likelihood of incomplete immunization in children decreased with the increase in household's income (aOR = 0.73, 95% CI [0.58-0.93]), children who did not have an immunization card (aOR = 13.41, 95% CI [9.19-19.57]) and those whose parents did not know that children immunization was free of charge (aOR = 1.82, 95% CI [1.00-3.30]) were more likely to have an incomplete immunization. Finally, children whose parents had to walk half an hour to one hour to reach a healthcare center were 57% (aOR = 1.57, 95% CI [1.15-2.13]) more likely to have an incomplete immunization coverage than those whose parents had to walk less than half an hour.

CONCLUSION

The goal of 90% coverage at the national level has not been achieved in 2017. Innovative strategies such as using electronic cards and strengthening sensitization activities must be initiated in order to attain a complete immunization coverage in Togo.

Children who have received no routine polio vaccines in Nigeria: Who are they and where do they live?

Nigeria has made remarkable progress against polio, but 2 wild polio virus cases were reported in August 2016; putting an end to 2 y without reported cases. We examined the extent of geographical disparities in childhren not vaccinated against polio and examined individual- and community-level predictors of non-vaccination in Nigeria. We applied multilevel logistic regression models to the recent Nigeria Demographic and Health Survey. The percentage of children not routinely vaccinated against polio in Nigeria varied greatly and clustered geographically, mainly in north-eastern states, with a great risk of spread of transmission within these states and potential exportation to neighboring states and countries. Only about one-third had received all recommended 4 routine oral polio vaccine doses. Non-vaccinated children tended to have a mother who had no formal education and who was currently not working, live in poorer households and were from neighborhoods with higher maternal illiteracy rates.