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

Trends and projections of age-appropriate vaccination coverage in 41 low- and middle- income countries in Asia and Sub-Saharan Africa, 2000-2030

Introduction

Routine immunization programs have focused on increasing vaccination coverage, which is equally important for decreasing vaccine-preventable diseases (VPDs), particularly in low- and lower-middle-income countries (LMICs). We estimated the trends and projections of age-appropriate vaccination coverage at the regional and national levels, as well as place of residence and wealth index in LMICs.

Methods

In total, 174 nationally representative household surveys from 2000 to 2020 from 41 LMICs were included in this study. Bayesian hierarchical regression models were used to estimate trends and projections of age-appropriate vaccination.

Results

The trend in coverage of age-appropriate Bacillus Calmette-Guérin (BCG), third dose of diphtheria, tetanus, and pertussis (DTP3), third dose of polio (polio3), and measles-containing vaccine (MCV) increased rapidly from 2000 to 2020 in LMICs. Findings indicate substantial increases at the regional and national levels, and by area of residence and socioeconomic status between 2000 and 2030. The largest rise was observed in East Africa, followed by South and Southeast Asia. However, out of the 41 countries, only 10 countries are estimated to achieve 90% coverage of the BCG vaccine by 2030, five of DTP3, three of polio3, and none of MCV. Additionally, by 2030, wider pro-urban and -rich inequalities are expected in several African countries.

Conclusion

Significant progress in age-appropriate vaccination coverage has been made in LMICs from 2000 to 2020. Despite this, projections show many countries will not meet the 2030 coverage goals, with persistent urban-rural and socioeconomic disparities. Therefore, LMICs must prioritize underperforming areas and reduce inequalities through stronger health systems and increased community engagement to ensure high coverage and equitable vaccine access.

Low Immunization Completion among Under-Five Children: Are Underserved Nomadic and Farming Communities in a North Central State of Nigeria doing Better?

Background

The recent drop in immunization coverage in Nigeria has left more than 3.25 million children unimmunized and has risen concern over immunization completion among the under-five children. More so among underserved communities of pastoralist nomads and farmers that were isolated from immunization services because of operational and sociocultural factors.

Materials and Methods

A cross-sectional analytical (comparative analysis) study was carried out among 550 eligible caregivers of under-five children in nomadic and farming communities in Niger State, Nigeria. The mothers and caregivers paired with under-five children were recruited into the study using a multistage sampling technique. Data was collected using a validated interviewer-administered questionnaire. Data was analyzed with the statistical software package (version 23).

Results

More than half of the under-five children studied were males in both the nomadic (57.5%) and farming (52.0%) communities. The aggregated score of immunization knowledge was significantly (P < 0.001) better (Good 44.4%; Fair 49.8%) among farmers compared to their nomads' counterpart (Good 21.1%; Fair 43.6%). Conversely, almost all the respondents (98.2%) in nomadic community significantly had a good overall perception of childhood immunization compared to 77.1% in the farming community. More farmers' children (99.6%) had received immunization compared to 92.4% of the nomads' children. About 87.3% of farmers compared to 76% of the nomads' (76.0%) children reported immunization completion. About 50.5% of the farmers' and 41.4% of the nomads' children have achieved immunization on card inspection.

Conclusion

This study revealed that average immunization completion reported among under-five children in both farming and nomadic communities is higher than the national average. It is recommended that more strategies are needed to intensify immunization campaigns targeted at populations in Nigeria.

Trends, projection and inequalities in full immunization coverage in Ethiopia: in the period 2000-2019

BACKGROUND

Immunization is among the most cost-effective health interventions to improve child survival. However, many countries in sub-Saharan Africa failed to achieve their national and international coverage targets repeatedly. The present study investigated trends of coverage and inequalities in coverage in Ethiopia.

METHODS

This study used data from five rounds of the Demographic and Health Surveys conducted in Ethiopia in 2000, 2005, 2011, 2016, and 2019. The surveys used a multistage cluster sampling procedure to obtain a nationally and sub-nationally representative data. The outcome variables included in the study were full immunization coverage and inequality. The World Health Organization's Health Equity Assessment Toolkit was used to conduct the inequality analysis. Projections for 2025 were based on smoothed averages generated using the demographic and health survey data from 2000 to 2019.

RESULTS

The full (basic) immunization coverage in Ethiopia has increased steadily from 14.3% in 2000 to 44.1% in 2019. Based on the average past performance, the immunization coverage is projected to reach 53.6% by 2025, which will be short of the 75% national full (basic) immunization coverage target for the year 2025. Mothers with higher levels of education are more likely to get their children all basic vaccinations than those with lower levels of education. Similarly, the inequality gaps due to wealth and residency are significant; where children in the lowest wealth strata and those living in rural areas remained disadvantaged.

CONCLUSION

Despite a steady increase in immunization coverage in the past two decades the country is yet to achieve its immunization target. Thus, more efforts are needed to achieve the current and future national immunization targets. A more focused intervention targeting the disadvantaged groups could be an effective strategy to achieve coverage and minimize the inequality gaps in immunization.

Estimating global and regional disruptions to routine childhood vaccine coverage during the COVID-19 pandemic in 2020: a modelling study

BACKGROUND

The COVID-19 pandemic and efforts to reduce SARS-CoV-2 transmission substantially affected health services worldwide. To better understand the impact of the pandemic on childhood routine immunisation, we estimated disruptions in vaccine coverage associated with the pandemic in 2020, globally and by Global Burden of Disease (GBD) super-region.

METHODS

For this analysis we used a two-step hierarchical random spline modelling approach to estimate global and regional disruptions to routine immunisation using administrative data and reports from electronic immunisation systems, with mobility data as a model input. Paired with estimates of vaccine coverage expected in the absence of COVID-19, which were derived from vaccine coverage models from GBD 2020, Release 1 (GBD 2020 R1), we estimated the number of children who missed routinely delivered doses of the third-dose diphtheria-tetanus-pertussis (DTP3) vaccine and first-dose measles-containing vaccine (MCV1) in 2020.

FINDINGS

Globally, in 2020, estimated vaccine coverage was 76·7% (95% uncertainty interval 74·3-78·6) for DTP3 and 78·9% (74·8-81·9) for MCV1, representing relative reductions of 7·7% (6·0-10·1) for DTP3 and 7·9% (5·2-11·7) for MCV1, compared to expected doses delivered in the absence of the COVID-19 pandemic. From January to December, 2020, we estimated that 30·0 million (27·6-33·1) children missed doses of DTP3 and 27·2 million (23·4-32·5) children missed MCV1 doses. Compared to expected gaps in coverage for eligible children in 2020, these estimates represented an additional 8·5 million (6·5-11·6) children not routinely vaccinated with DTP3 and an additional 8·9 million (5·7-13·7) children not routinely vaccinated with MCV1 attributable to the COVID-19 pandemic. Globally, monthly disruptions were highest in April, 2020, across all GBD super-regions, with 4·6 million (4·0-5·4) children missing doses of DTP3 and 4·4 million (3·7-5·2) children missing doses of MCV1. Every GBD super-region saw reductions in vaccine coverage in March and April, with the most severe annual impacts in north Africa and the Middle East, south Asia, and Latin America and the Caribbean. We estimated the lowest annual reductions in vaccine delivery in sub-Saharan Africa, where disruptions remained minimal throughout the year. For some super-regions, including southeast Asia, east Asia, and Oceania for both DTP3 and MCV1, the high-income super-region for DTP3, and south Asia for MCV1, estimates suggest that monthly doses were delivered at or above expected levels during the second half of 2020.

INTERPRETATION

Routine immunisation services faced stark challenges in 2020, with the COVID-19 pandemic causing the most widespread and largest global disruption in recent history. Although the latest coverage trajectories point towards recovery in some regions, a combination of lagging catch-up immunisation services, continued SARS-CoV-2 transmission, and persistent gaps in vaccine coverage before the pandemic still left millions of children under-vaccinated or unvaccinated against preventable diseases at the end of 2020, and these gaps are likely to extend throughout 2021. Strengthening routine immunisation data systems and efforts to target resources and outreach will be essential to minimise the risk of vaccine-preventable disease outbreaks, reach children who missed routine vaccine doses during the pandemic, and accelerate progress towards higher and more equitable vaccination coverage over the next decade.

FUNDING

Bill & Melinda Gates Foundation.

Inequities in childhood immunisation coverage associated with socioeconomic, geographic, maternal, child, and place of birth characteristics in Kenya

BACKGROUND

The global Immunisation Agenda 2030 highlights coverage and equity as a strategic priority goal to reach high equitable immunisation coverage at national levels and in all districts. We estimated inequities in full immunisation coverage associated with socioeconomic, geographic, maternal, child, and place of birth characteristics among children aged 12-23 months in Kenya.

METHODS

We analysed full immunisation coverage (1-dose BCG, 3-dose DTP-HepB-Hib (diphtheria, tetanus, pertussis, hepatitis B and Haemophilus influenzae type B), 3-dose polio, 1-dose measles, and 3-dose pneumococcal vaccines) of 3943 children aged 12-23 months from the 2014 Kenya Demographic and Health Survey. We disaggregated mean coverage by socioeconomic (household wealth, religion, ethnicity), geographic (place of residence, province), maternal (maternal age at birth, maternal education, maternal marital status, maternal household head status), child (sex of child, birth order), and place of birth characteristics, and estimated inequities in full immunisation coverage using bivariate and multivariate logistic regression.

RESULTS

Immunisation coverage ranged from 82% [81-84] for the third dose of polio to 97.4% [96.7-98.2] for the first dose of DTP-HepB-Hib, while full immunisation coverage was 68% [66-71] in 2014. After controlling for other background characteristics through multivariate logistic regression, children of mothers with primary school education or higher have at least 54% higher odds of being fully immunised compared to children of mothers with no education. Children born in clinical settings had 41% higher odds of being fully immunised compared to children born in home settings. Children in the Coast, Western, Central, and Eastern regions had at least 74% higher odds of being fully immunised compared to children in the North Eastern region, while children in urban areas had 26% lower odds of full immunisation compared to children in rural areas. Children in the middle and richer wealth quintile households were 43-57% more likely to have full immunisation coverage compared to children in the poorest wealth quintile households. Children who were sixth born or higher had 37% lower odds of full immunisation compared to first-born children.

CONCLUSIONS

Children of mothers with no education, born in home settings, in regions with limited health infrastructure, living in poorer households, and of higher birth order are associated with lower rates of full immunisation. Targeted programmes to reach under-immunised children in these subpopulations will lower the inequities in childhood immunisation coverage in Kenya.