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Clinical Trial

Asymptomatic Malaria Infection and the Immune Response to the 2-Dose Ad26.ZEBOV, MVA-BN-Filo Ebola Vaccine Regimen in Adults and Children

D Ishola et al. Clin Infect Dis. .

Abstract

Background: Malaria infection affects the immune response to some vaccines. As Ebola virus (EBOV) outbreaks have occurred mainly in malaria-endemic countries, we have assessed whether asymptomatic malaria affects immune responses to the 2-dose Ad26.ZEBOV, MVA-BN-Filo Ebola vaccine regimen.

Methods: In this sub-study of the EBOVAC-Salone Ebola vaccine trial in Sierra Leone, malaria microscopy was performed at the time of Ebola vaccination. Participants with symptomatic malaria were treated before vaccination. Ebola vaccine responses were assessed post-dose 1 (day 57) and post-dose 2 (day 78) by the EBOV glycoprotein FANG enzyme-linked immunosorbent assay (ELISA), and responses expressed as geometric mean concentrations (GMCs). Geometric mean ratios (GMRs) of the GMCs in malaria-positive versus malaria-negative participants were derived with 95% confidence intervals (CIs).

Results: A total of 587 participants were studied, comprising 188 adults (≥18 years) and 399 children (in age groups of 12-17, 4-11, and 1-3 years). Asymptomatic malaria was observed in 47.5% of adults and 51.5% of children on day 1. Post-dose 1, GMCs were lower in 1-3-year-old malaria-positive compared with malaria-negative children (age group-specific GMR, .56; 95% CI, .39-.81) but not in older age groups. Post-dose 2, there was no consistent effect of malaria infection across the different age groups but there was a trend toward a lower response (GMR, .82; 95% CI, .67-1.02).

Conclusions: The Ad26.ZEBOV, MVA-BN-Filo Ebola vaccine regimen is immunogenic in participants with asymptomatic malaria. Therefore, it is not necessary to screen for asymptomatic malaria infection prior to vaccination with this regimen.

Keywords: Ebola vaccination; immune suppression; malaria.

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Conflict of interest statement

Potential conflicts of interest . A. G., B. K., D. A., and V. B. were full-time employees of Janssen, Pharmaceutical Companies of Johnson & Johnson, at the time of the study, and declared ownership of shares in Janssen, Pharmaceutical Companies of Johnson & Johnson. C. R. is an employee of Janssen Pharma and receives stock options as compensation. D. M. reports grants from Innovative Medicines Initiative (IMI), nonfinancial support and other from Janssen Vaccines & Prevention B.V. during the conduct of the study; and grants and nonfinancial support from Janssen Vaccines & Prevention B.V. outside the submitted work. K. G. reports grants from IMI during the conduct of the study. P. Akoo reports travel support (tickets and accommodation support) for attending EBOVAC-1 meetings. D. I. reports employment with LSHTM on the EBOVAC-3 project, as well as support for project travel and meeting costs from LSHTM on the EBOVAC-1 and EBOVAC-3 projects, both funded by the IMI of the European Union. D. W.-J. reports funding outside the scope of this work for the EBOVAC-3 project provided by the IMI of the European Union and Janssen, Pharmaceutical Companies of Johnson & Johnson. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.

Figures

Figure 1.
Figure 1.
Study participants.
Figure 2.
Figure 2.
Geometric mean ratios of EBOV GP–specific binding antibody GMCs, in malaria parasite-positive and -negative individuals by age. The effects of malaria infection, as determined by microscopy, at the time of vaccination on postvaccination antibody concentrations for dose 1 (A) and for dose 2 (B) are shown. Abbreviations: CI, confidence interval; EBOV, Ebola virus; GP, glycoprotein; GMC, geometric mean concentration; GP, glycoprotein.
Figure 3.
Figure 3.
Correlation between malaria parasite density at the time of vaccination, and postvaccination antibody concentrations by age group: dose 1 (upper panels), dose 2 (lower panels). Abbreviations: EBOV, Ebola virus; GP, glycoprotein; IgG, immunoglobulin G.
See this image and copyright information in PMC

References

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