Peer-reviewed article
Routine Immunisation and Under-Five Mortality in Least Developed Countries: Longitudinal Evidence on Vaccine-Specific Moderation by Government Health Expenditure
Onome Bendalene Irikefe, Bernard Ojonugwa Anthony, Precious Suru Uleyo, Jonathan Ojarikre Oniore ·
Summary
Written by AI, not yet AICS's view · claude-sonnet-5This study looked at how routine childhood vaccination rates relate to under-five death rates across 41 of the world's least developed countries between 2000 and 2023. It examined six specific vaccines separately and checked whether government health spending changed the strength of these relationships. The researchers also looked at whether vaccine effects differed for countries with especially high child mortality. Some vaccines, like DTP3 and polio, showed clear links to lower child deaths, while others like hepatitis B and BCG did not show a clear average effect. Government spending patterns and household out-of-pocket costs also mattered for child survival.
Key points
- A 1% increase in DTP3, measles, Hib3, and polio vaccine coverage was linked to reductions in under-five mortality of 0.229%, 0.162%, 0.072%, and 0.243% respectively.
- HepB3 and BCG coverage showed no significant average association with under-five mortality.
- Government health expenditure weakened the protective link for DTP3, measles, BCG, and polio vaccines, but strengthened it for HepB3.
- Vaccine effects were generally strongest in countries or periods with the highest mortality levels.
- Out-of-pocket health spending was linked to higher mortality, while GDP per capita and basic sanitation coverage were linked to lower mortality.
Limitations
The analysis uses country-level (ecological) data rather than individual child records, so it cannot show what happens to specific children, and results may not generalise beyond the least developed countries studied.
Abstract
Background Under-five mortality remains disproportionately high in least developed countries (LDCs), despite expanded access to routine childhood immunisation. This study examined six vaccine-specific associations with under-five mortality, the moderating role of government health expenditure (GHE), and variation across the mortality distribution. Methods An ecological longitudinal panel of 41 LDCs covering 2000 to 2023 was analysed. Six vaccine-specific models were estimated separately using country fixed effects with Driscoll-Kraay standard errors. Moderation was assessed using interactions between within-country-centred vaccine coverage and GHE. Split-panel jackknife method-of-moments quantile regression evaluated effects at the 25th, 50th, and 75th conditional quantiles. Results The findings showed vaccine-specific asymmetry, with direct and GHE-moderated effects varying in magnitude, significance and direction across the six vaccines. A 1% increase in coverage of the third dose of the diphtheria-tetanus-pertussis vaccine (DTP3), measles-containing vaccine (MCV), third dose of the Haemophilus influenzae type b vaccine (Hib3), and third dose of the polio vaccine (Pol3) was associated with reductions in under-five mortality of 0.229%, 0.162%, 0.072%, and 0.243%, respectively. Coverage of the third dose of the hepatitis B vaccine (HepB3) and Bacillus Calmette-Guérin vaccine (BCG) showed no significant average association. GHE attenuated the inverse associations for DTP3, MCV, BCG, and Pol3, strengthened the HepB3 association, and did not significantly moderate Hib3. Vaccine effects were generally strongest at the upper mortality quantile. Out-of-pocket health expenditure was positively associated with mortality, whereas gross domestic product per capita and basic sanitation coverage were inversely associated. Conclusions Routine immunisation was associated with improved child survival in LDCs, but the benefits varied by vaccine, financing conditions, and mortality level. Policies should prioritise effective delivery, preventive expenditure, and high-mortality populations.
Findings the Hub has extracted
Each claim below is labelled by its type of design and links back to this report.
Problem
High under-five mortality in least developed countries despite expanding immunisation programmes.
- Intervention
- Routine childhood immunisation with six vaccines (DTP3, measles, Hib3, polio, hepatitis B, BCG)
- Population
- Under-five children in 41 least developed countries, 2000-2023
Key finding
DTP3, measles, Hib3, and polio coverage increases were associated with mortality reductions of 0.229%, 0.162%, 0.072%, and 0.243% respectively.
Irikefe et al. · OpenAlex · 21 Aug 2026