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Abstract
Introduction Malaria continues to be a major cause of morbidity and mortality in sub-Saharan Africa (SSA) without effective interventions. Bacillus Calmette-Guérin (BCG) vaccine possesses protective non-specific effects, which extend beyond protection against tuberculosis. This study explores whether BCG is associated with protection against malaria in children under the age of 5 years in SSA.
Methods We used data from the Demographic Health Survey programme, including 34 206 children from 13 SSA countries. BCG status was taken from vaccination cards when present; if not, mother’s recall was used. Presence of malaria was defined as a positive rapid diagnostic test. Maternally reported presence or absence of fever in the previous 2 weeks defined symptomatic status. Multilevel logistic regression was used to account for the two-stage cluster sampling method.
Results Of the 34 206 children, 12 325 (36.0%) children were malaria positive and 29 766 (87.0%) were BCG vaccinated. After correction for relevant child, maternal and household factors, BCG vaccination was associated with a lower malaria prevalence (adjusted OR (aOR)=0.94, 95% CI 0.90 to 0.98), especially among children of whom BCG information was retrieved from a vaccination card (aORcard=0.88, 95% CI 0.82 to 0.94). Restricting the analysis to children from regions with suboptimal BCG coverage increased the association (aORcard=0.81, 95% CI 0.73 to 0.89). We observed an increasingly beneficial association with each month of age of the child (aORcard=0.996, 95% CI 0.993 to 0.999). BCG associations were similar for asymptomatic (aORcard=0.86, 95% CI 0.81 to 0.92) and symptomatic (aORcard=0.89, 95% CI 0.78 to 1.01) malaria.
Conclusions BCG vaccination is associated with protection against malaria. This protection is highest in regions with suboptimal BCG coverage. These results indicate a possible role for timely BCG vaccination in the protection of malaria and its elimination by reducing the transmission reservoir. If confirmed in further research, our findings have substantial implications for global efforts to reduce malaria burden.
- bacillus Calmette-Guérin
- heterologous effects
- malaria
- DHS
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Footnotes
Handling editor Sanni Yaya
Contributors JS, MN and AvdV conceptualised the study. MB and SvG prepared the database and carried out the first analyses. MB and JS refined and performed the final analyses. QdM, PA, CSB, MN and AvdV contributed to interpretation of the data. MB and SvG wrote the first draft. QdM, JS, PA, CSB, MN and AvdV revised the article critically on intellectual content. All authors contributed to and approved the final manuscript and agreed to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The corresponding author attests that all listed authors meet authorship criteria and that no others meeting the criteria have been omitted.
Funding CSB was supported by the Danish National Research Foundation (DNRF108) through general support for the CVIVA institute. AvdV was supported by an unrestricted grant from Sysmex Corporation. The funding sources had no role in study design, data collection and analysis, interpretation of data, preparation of the manuscript or decision to submit for publication. The corresponding author had full access to all the data in the study and had final responsibility for the decision to submit for publication.
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Competing interests All authors have completed the Unified Competing Interest form (www.icmje.org/coi_disclosure.pdf) and declare no support from companies for the submitted work; no financial relationships with companies that might have an interest in the submitted work in the previous 3 years; their spouses, partners or children have no financial relationships that may be relevant to the submitted work; no non-financial interests that may be relevant to the submitted work.
Patient consent for publication Not required.
Ethics approval The team executing the Demographic Health Survey ensures protection of human subjects in agreement with local and international laws.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement The data were obtained from the DHS program (www.dhsprogram.com) under the condition that the authors do not pass the data to other researchers. However, other researchers can apply directly to the DHS program to obtain the data.