Background
Methods
Searches
Study exclusion and inclusion criteria
Potential effect modifiers and reasons for heterogeneity
Study quality assessment
Data extraction strategy
Data synthesis and presentation
metafor
to produce estimates of the risk ratio of full immunisation for each subpopulation; p-values were calculated using a chi-squared test [17]. We used an empirical Bayes estimator for the level of heterogeneity and weighted by the size of the population. We performed five hypothesis tests 4, each evaluating the null hypothesis that the risk of full immunisation is the same across two levels of a socio-demographic characteristic of interest. We declared significance if a p-value was below 0.01, which was chosen after applying the Bonferroni correction to our starting significance level of 0.05 and taking into the account the five tests. Additional information is provided in the supplementary index. Adjusted risk ratios were not calculated as it was not possible to link covariates for the majority of the available data. Analyses were conducted using R version 4.0.3. Data and code are available from https://github.com/mrc-ide/vaccinequity_litreview.Results
Overview
Study characteristics
Study quality
The effect of inequality in vaccination coverage on the impact of vaccination
Geographic variation in vaccination coverage
Quantitative synthesis of rural-urban differences in vaccination coverage
Demographic variation in vaccination coverage
Quantitative synthesis of gender differences in vaccination coverage
Socioeconomic variation in vaccination coverage
Effect of wealth, occupation, and martial status on immunisation coverage
Effect of education on immunisation coverage
Quantitative synthesis of maternal education differences in vaccination coverage
Quantitative synthesis of wealth quintile differences in vaccination coverage
Barriers to vaccine access in low and middle income countries
Summary
Discussion
Conclusions
Appendix A: Supplementary material
Age range of study participants
Additional meta-analysis results
Quantitative synthesis of maternal marital status differences in vaccination coverage
Summary of meta-analysis results & insights into Uthman et al. exclusion
Attribute | # Studies | Meta-analysis Result | Heterogeneity |
---|---|---|---|
Urban/Rural | 24 | No significant pooled effect | Wide heterogeneity between countries with, for example, all studies in China suggesting a positive risk ratio and all studies in Ethiopia suggesting a negative risk ratio. |
Gender | 26 | Significant risk ratio to being fully vaccinated given female com-pared to male of 0.97 (95%CI [0.95, 0.99]) suggesting females are 3% (95%CI[1%,5%]) less likely to be vaccinated than their male counterparts | General consensus between countries and time periods with almost all studies either spanning one or with significantly negative risk ratio. |
Education | 16 | Risk ratio to a child being vaccinated given their mother has no formal education compared to having any education level ie. primary or above, as 0.73 (95%CI [0.64, 0.84]); this model fit is significant. This implies that children are 27% (95%CI [16%,36%]) less likely to be fully vaccinated if their mother has no formal education. | |
Wealth | 18 | Risk ratio of 0.73 (95%CI [0.63, 0.84]) to being vaccinated ifin the poorest wealth quintile compared to richest; individuals in the poorest subpopulations are 27% (95%CI [16%,37%]) less likely to be fully vaccinated than those in the richest. | |
Marital Status | 7 | No significant pooled effect | General consensus between countries and time periods, almost all studies had risk ratios spanning one. One study had a significantly positive risk ratio [24] which covered Sub-Saharan Africa. |
Characteristic | Risk ratio | p-value | Significant given Bonferroni correction |
---|---|---|---|
Gender | 0.96 (95%CI[0.95, 0.98]) | 4 ×10−4 | Yes |
Wealth | 1.85 (95%CI[1.44, 2.38]) | 1.96 ×10−6 | Yes |
Urban/Rural | 1.00 (95%CI[0.93, 1.08]) | 0.91 | No |
Maternal education | 0.72 (95%CI[0.63, 0.82]) | 1.22 ×10−6 | Yes |
Maternal marital status | 1.02 (95%CI[0.99, 1.05]) | 0.25 | No |
Multiple testing considerations
Summary of definitions of fully immunised utilised across studies
Immunisations Included | N (%) | Studies |
---|---|---|
1974 EPI Vaccines (At least one each dose of DTP, MCV, BCG, & OPV/IPV) | 41 (37.96%) | |
1974 EPI Vaccines & HBV | 10 (9.26%) | |
1974 EPI vaccines, HBV, & MMR | 2 (1.85%) | |
1974 EPI vaccines, HBV, & JE | 2 (1.85%) | |
1974 EPI Vaccines, HBV, & Hib | 7 (6.48%) | |
1974 EPI Vaccines, HBV, Hib, & YF | 2 (1.85%) | |
1974 EPI Vaccines, HBV, Hib, & MMR | 2 (1.85%) | |
DTP, MCV, & BCG | 4 (3.70%) | |
DTP & MCV | 4 (3.70%) | |
DTP | 4 (3.70%) | |
MCV | 11 (10.12%) | |
Polio (OPV/IPV) | 3 (2.78%) | |
HBV | 3 (2.78%) | |
Influenza | 2 (1.85%) | |
Other | 7 (6.48%) | |
Not given | 4 (3.70%) |
All studies
Year* | Author* | Study type | Vaccine | Country | Min age | Max age | Grade | Year of data |
---|---|---|---|---|---|---|---|---|
2012 | Abebe | cross-sectional | 1974 EPI vaccines: BCG, polio, measles, DTP | MALAWI | 0 | 5 | A | 2007 |
2019 | Adebowale | cross-sectional | 1974 EPI vaccines: BCG, polio, measles, DTP | NIGERIA | 1 | 2 | D | 2013 |
2017 | Ambel | cross-sectional | 1974 EPI vaccines: BCG, polio, measles, DTP | ETHIOPIA | 1 | 2 | A | 2000 - 2014 |
2020 | Ameyaw | Cross-sectional | 1974 EPI vaccines: BCG, polio, measles, DTP | VARIOUS | 1 | 2 | A | 2010 - 2018 |
2017 | Andrade | cross sectional-ecological study, household survey | Tetanus | BRAZIL | 0 | 5.0 | A | 2012 |
2010 | Antai | cross-sectional | 1974 EPI vaccines: BCG, polio, measles, DTP | NIGERIA | 1 | 1 | A | 2003 |
2013 | Arokiasamy | secondary data analysis | 1974 EPI vaccines: BCG, polio, measles, DTP | INDIA | 1 | 1.92 | A | 2005 - 2006 |
2017 | Arsenault | random-effects meta-analyses using DHS data | DTP & MCV | VARIOUS | 1 | 2 | B | 2005 - 2014 |
2017 | Arsenault | random-effects meta-regression analyses using DHS data | DTP & MCV | VARIOUS | 1 | 2 | B | 2005 - 2014 |
2019 | Asif | Multilevel logistic regression on individual and community level data using DHS data | 1974 EPI vaccines: BCG, polio, measles, DTP | PAKISTAN | 1 | 5 | B | 2012 - 2013 |
2016 | Ataguba | secondary questionnaire household data | 1974 EPI vaccines + Hep B + Hib + YF | NIGERIA | 1 | 5 | B | 2006 |
2008 | Boerma | secondary DHS data | DTP, MCV, & BCG | VARIOUS | 1 | 2 | B | 1990 - 2006 |
2003 | Bonu | cross-sectional surveys based on systematic,stratified samples of households | 1974 EPI vaccines: BCG, polio, measles, DTP | INDIA | 1 | 3 | B | 1992 - 1999 |
2004 | Bonu | cross-sectional DHS household survey | 1974 EPI vaccines: BCG, polio, measles, DTP | VARIOUS | 1 | 2 | B | NA |
2012 | Bosch-Caplanch | secondary DHS and MICS data | 1974 EPI vaccines: BCG, polio, measles, DTP | VARIOUS | 1 | 5 | B | 1986 - 2007 |
2018 | Boulton | secondary DHS data | 1974 EPI vaccines + Hep B + Hib (aka penta for some studies) | BANGLADESH | 1 | 2 | A | 2014 |
2014 | Castelo Branco | cross-sectional | 1974 EPI vaccines + Hep B + Hib + YF + MR (mumps/Rubella) | BRAZIL | 1 | 4.92 | A | 2010 |
2021 | Cata-Preta | secondary data from DHS and MICS | 1974 EPI vaccines: BCG, polio, measles, DTP | VARIOUS | 1 | 2.42 | A | 2010 - 2019 |
2019 | Chakrabarti | secondary r supplementary immunization activities data | 1974 EPI Vaccines + Hep B (HBV) | VARIOUS | 1 | 5 | C | 1996 - 2013 |
2003 | Chowdhury | secondary data | 1974 EPI vaccines: BCG, polio, measles, DTP | BANGLADESH | 1 | 2 | B | 1993 - 1994, 1996 - 1997, 1999 - 2000 |
2014 | Clouston | secondary DHS data | 1974 EPI vaccines + Hep B + Hib (aka penta for some studies) | MADAGASCAR | 0 | 4 | B | 2008 - 2009 |
2013 | Cui | national stratified, validation, cross-sectional survey | Hep B | CHINA | 0 | 1.0 | B | 2002 - 2009 |
2016 | Devasenapathy | cross sectional, household survey | 1974 EPI Vaccines + Hep B (HBV) | INDIA | 1 | 3.5 | A | 2014 |
2016 | Devkota | Pooled cross-sectional series | 1974 EPI Vaccines + Hep B (HBV) | NEPAL | 0 | 5 | B | 2003 - 2011 |
2015 | Egondi | Cross-Sectional Slum Survey of 2012 | 1974 EPI vaccines + Hep B + Hib (aka penta for some studies) | KENYA | 1 | 1.92 | B | 2012 |
2011 | Fernandez | Secondary census data | Measles | INDONESIA | 0 | 5 | B | 2007 |
2007 | Fotso | secondary data analysis | 1974 EPI vaccines: BCG, polio, measles, DTP | VARIOUS | 1 | 2 | C | 1990 - 2006 |
2020 | Gao | secondary DHS and MICS data | Measles | VARIOUS | 1 | 2 | A | 2014 - 2017 |
2006 | Gaudin | secondary data analysis | 1974 EPI vaccines: BCG, polio, measles, DTP | INDIA | 1 | 5.0 | A | 1992 - 1999 |
2020 | Geweniger | Secondary data analysis | 1974 EPI vaccines + Hep B + Hib + PCV + Rota | ETHIOPIA | 1 | 1.92 | A | 2016 |
2020 | Goli | secondary data analysis | 1974 EPI vaccines: BCG, polio, measles, DTP | INDIA | 1 | 2 | C | 2015 - 2016 |
2013 | Goli | secondary data analysis | Missing/Not given | INDIA | 1 | 1.92 | A | 2005 - 2006 |
2012 | Goodson | Nationwide cross-sectional survey | Measles | MADAGASCAR | 0.75 | 4.92 | B | 2007 |
2005 | Grabowsky | single population-based survey | Measles | ZAMBIA | 0.5 | 4.92 | B | 2003 |
2014 | Gram | Secondary data analysis | 1974 EPI vaccines + Hep B + Hib + YF | GHANA | 0 | 1.0 | B | 2011 |
2014 | Grundy | secondary data analysis | DTP | VARIOUS | NA | NA | A | NA |
2008 | Gupta | sample survey of households | 1974 EPI vaccines + Hep B + Hib + MR | INDIA | 0 | 5 | B | 2006 |
2018 | Hajizadeh | Secondary data analysis | BCG, polio, DTP, measles | VARIOUS | 0.83 | 4.92 | A | 2010 - 2015 |
2019 | Hajizadeh | Secondary dataanalysis | 1974 EPI vaccines: BCG, polio, measles, DTP | GAMBIA, KYRGYZREPUBLIC, NAMIBIA | 0 | 4.92 | A | 2012, 2013 |
2018 | Hanifi | Secondary dataanalysis | 1974 EPI vaccines + Hep B + Hib (aka penta for some studies) | BANGLADESH | 1 | 1.92 | A | 2012 - 2016 |
2014 | Helleringer | secondary data analysis | Polio | VARIOUS | 1 | 2 | A | NA |
2017 | Herliana | Cross-sectional | 1974 EPI Vaccines + Hep B (HBV) | INDONESIA | 1 | 5 | B | 2012 |
2009 | Hong | secondary data analysis | DTP | CAMBODIA | 0 | 1.0 | A | 2000 - 2005 |
2016 | Hosseinpoor | secondary data analysis | DTP | VARIOUS | 1 | 1.92 | C | 2000 - 2013 |
2003 | Houweling | secondary data analysis | Measles | VARIOUS | 1 | 1.92 | A | 1991 - 1998 |
2018 | Hu | secondary data analysis | 1974 EPI vaccines + Hep B + JE | CHINA | 2 | 3 | A | 2014, 2017 |
2019 | Hu | secondary data analysis | 1974 EPI vaccines + Hep B + MR | CHINA | 2 | 3 | A | 2016 |
2017 | Hu | secondary data analysis | 1974 EPI vaccines + Hep B + JE | CHINA | 2 | 2.92 | A | 2014 |
2018 | Imran | Secondary data analysis | Polio | PAKISTAN | 1 | 1.92 | A | 1990 - 1991 |
2020 | Joseph | secondary data analysis | 1974 EPI Vaccines + PCV | KENYA | 1 | 1.92 | A | 2014 |
2017 | Joshi | multiple indicator cluster surveys | 1974 EPI vaccines + Hep B + Hib + MR | MONGOLIA | 0 | 5.0 | A | 2000, 2005, 2010 |
2021 | Kannankeril | Secondary data analysis | BCG, polio, DTP, measles | INDIA | 1 | 1.92 | A | 2015 - 2016 |
2017 | Kasuma | cluster randomised trial | 1974 EPI Vaccines + Hep B (HBV) | INDONESIA | 1 | 1.92 | A | 2007 - 2009 |
2016 | KC | Secondary data analysis | BCG, polio, DTP, measles | NEPAL | 0 | 1.0 | A | 2001 - 2014 |
2011 | Khan | secondary data analysis | DTP, MCV, & BCG | BANGLADESH | 0 | 5.0 | A | 1993 - 2007 |
2011 | Khowaja | secondary data analysis | 1974 EPI Vaccines + Hep B (HBV) | PAKISTAN | 1 | 1.92 | A | 2008 |
2016 | Kumar | secondary data analysis | 1974 EPI vaccines: BCG, polio, measles, DTP | INDIA | 1 | 1.92 | A | 1990 - 2006 |
2013 | Kumar | secondary data analysis | DTP, MCV, & BCG | INDIA | 1 | 1.92 | B | NA |
2015 | Lanaspa | secondary data analysis | 1974 EPI vaccines + Hep B + Hib (aka penta for some studies) | MOZAMBIQUE | 0 | 5 | A | 2012 |
2020 | LBDVCC | secondary data analysis and modelling | Measles | VARIOUS | 0 | 5.0 | A | 2000 - 2019 |
2016 | Li | cross-sectional survey? | Influenza | CHINA | 60 | 100.0 | A | 2013 |
2010 | Limwattananon | secondary data analysis | 1974 EPI vaccines + Hep B + MR | THAILAND | 1 | 2 | A | 2005 - 2006 |
2016 | Lv | Cross-sectional surveys | Influenza | CHINA | 60 | NA | A | 2012 |
2015 | Martins | Cross-sectional surveys | Hep B | BRAZIL | 18 | 100.0 | A | 2012 - 2013 |
2007 | Mashal | secondary data analysis | 1974 EPI vaccines: BCG, polio, measles, DTP | AFGHANISTAN | 0 | 1 | D | 2000 - 2003 |
1997 | Matthews | Secondary data analysis | 1974 EPI vaccines: BCG, polio, measles, DTP | GHANA | 0 | 5.0 | C | 1988 |
2006 | Mfenyana | Cross-sectional surveys | Missing/Not given | SOUTH AFRICA | 0 | 5 | B | 1999 |
2007 | Minh Thang | Secondary data analysis | 1974 EPI vaccines: BCG, polio, measles, DTP | VIETNAM | 0.917 | 1.92 | D | 2002 |
2020 | Mishra | secondary data analysis | 1974 EPI Vaccines + Hep B (HBV) | INDIA | 1 | 5.0 | B | NA |
2009 | Mohanty | secondary data analysis | 1974 EPI vaccines: BCG, polio, measles, DTP | INDIA | 1 | 1.92 | B | 1992 - 2006 |
2021 | Muche Fenta | secondary data analysis | 1974 EPI vaccines: BCG, polio, measles, DTP | VARIOUS | 1 | 1.92 | A | 2013 - 2017 |
2020 | Nda’chi Deffo | secondary DHS data | 1974 EPI vaccines: BCG, polio, measles, DTP | CAMEROON | 0.83 | 5 | A | 1991 - 2011 |
2021 | Ndwandwe | Secondary data analysis | 1974 EPI vaccines: BCG, polio, measles, DTP | SOUTH AFRICA | 1 | 1.92 | B | 2016 |
2011 | Nkonki | secondary data analysis | DTP, BCG, OPV | SOUTH AFRICA | 0 | 0.461 | A | NA |
2019 | Nozaki | Secondary data analysis | DTP, MCV, & BCG | MYANMAR | 1 | 1.92 | A | 2015 |
2017 | Ntenda | secondary data analysis | 1974 EPI vaccines: BCG, polio, measles, DTP | MALAWI | 1 | 1.92 | A | 2004, 2010 |
2017 | Oryema | cluster survey | 1974 EPI vaccines + Hep B + Hib (aka penta for some studies) | UGANDA | 0 | 5.0 | A | 2013 |
2003 | Pande | secondary data analysis | 1974 EPI vaccines: BCG, polio, measles, DTP | INDIA | 1 | 5.0 | B | 1992 - 1993 |
2020 | Portnoy | secondary data analysis | Measles | VARIOUS | 0 | 5.0 | A | NA |
2018 | Portnoy | secondary data analysis | Measles | VARIOUS | 0 | 5.0 | A | NA |
2013 | Prakash | secondary data analysis | 1974 EPI vaccines: BCG, polio, measles, DTP | INDIA | 0 | 5.0 | A | 2005 - 2006 |
2014 | Prusty | DHS but broken down by gender coverage ratio | 1974 EPI vaccines: BCG, polio, measles, DTP | INDIA | 1 | 1.92 | A | 1992 - 2006 |
2015 | Rammohan | secondary data analysis | DTP & MCV | INDIA | 1 | 5 | A | 2008 |
2018 | Raza | DHS | 1974 EPI vaccines + Hep B + Hib (aka penta for some studies) | PAKISTAN | NA | NA | A | 2012 - 2013 |
2016 | Restrepo-Méndez | secondary data analysis | 1974 EPI vaccines: BCG, polio, measles, DTP | VARIOUS | 0 | 18.0 | A | 2001 - 2012 |
2016 | Restrepo-Méndez | secondary data analysis | 1974 EPI vaccines: BCG, polio, measles, DTP | VARIOUS | 1 | 2.0 | A | 2000 - 2013 |
2017 | Sanoussi | secondary data analysis | Missing/Not given | TOGO | 0 | 5 | A | 1998 - 2013 |
2010 | Semali | secondary data analysis | 1974 EPI vaccines: BCG, polio, measles, DTP | TANZANIA | 1 | 1.92 | C | 1990, 1996, 2004 |
2020 | Shibre | secondary data analysis | Measles | ETHIOPIA | 1 | 1.92 | A | 2000, 2005, 2011, 2016 |
2014 | Sissoko | Secondary data analysis | 1974 EPI vaccines: BCG, polio, measles, DTP | INDIA | 1 | 1.92 | A | 2007 - 2008 |
2013 | Soeung | Secondary data analysis | DTP & MCV | CAMBODIA | NA | NA | C | 2000 - 2010 |
2020 | Song | Secondary data analysis | 1974 EPI vaccines: BCG, polio, measles, DTP | NEPAL | 1 | 1.92 | A | 2016 |
2015 | Soura | Secondary data analysis | 1974 EPI vaccines: BCG, polio, measles, DTP | VARIOUS | 1 | 5 | C | 2010 - 2015 |
2019 | Sowe | Secondary data analysis | 1974 EPI vaccines: BCG, polio, measles, DTP | GAMBIA | 1 | 1.92 | A | 2013 |
2020 | Srivastava | secondary data analysis | 1974 EPI Vaccines + Hep B (HBV) | INDIA | 1 | 5.0 | A | 2015 - 2016 |
2015 | Tsawe | secondary data analysis | Missing/Not given | Eswatini | 0 | 18.0 | A | 2006 - 2007 |
2016 | Uddin | multiple surveys | DTP, Hep B, Hib, MR (measles/Rubella), BCG | BANGLADESH | 1 | 1.92 | A | 2013 - 2014 |
2017 | Uthman | secondary data analysis | Polio | NIGERIA | 1 | 1.92 | A | 2013 |
2017 | Uzochukwu | Cross-sectional with cluster sampling design | 1974 EPI Vaccines + Hep B (HBV) | NIGERIA | 0.75 | 5 | B | 2016 |
2017 | van den Ent | Cross-sectional surveys | DTP | MADAGASCAR | NA | NA | C | 2013 - 2015 |
2013 | Van Malderen | Secondary dataanalysis | Measles | KENYA | 1 | 1.92 | B | 2008 - 2009 |
2012 | Victora | secondary data analysis | Measles | VARIOUS | NA | NA | A | NA |
2021 | Wahl | secondary data analysis | 1974 EPI vaccines: BCG, polio, measles, DTP | INDIA | 1 | 2 | A | 2005 - 2016 |
2019 | Wariri | secondary data analysis | DTP & BCG | VARIOUS | 1 | 1.92 | A | NA |
2019 | Wuneh | secondary data analysis | 1974 EPI vaccines: BCG, polio, measles, DTP | ETHIOPIA | 0.5 | 1.92 | A | 2016 - 2017 |
2017 | Xeuatvongsa | nationwide population-based cross-sectionalstudy that used data obtained through multistage cluster sampling | 1974 EPI vaccines: BCG, polio, measles, DTP | LAOS | 1 | 2.92 | A | 2014 |
2005 | Xie | secondary dataanalysis | 1974 EPI Vaccines + Hep B (HBV) | CHINA | 0 | 7 | A | 1991 - 1997 |
2019 | Yang | secondary data analysis | Hep B | CHINA | 16 | 45+ | A | 2008 - 2009 |