Background Malaria Incidence and Parasitemia during the Three-Dose RTS,S/AS01 Vaccination Series Do not Reduce Magnitude of Antibody Response nor Efficacy against the First Case of Malaria

Citation

Bell, Griffin J.; Gyaase, Stephaney; Goel, Varun; Adu, Bright; Mensah, Benedicta A.; Essone, Paulin; Dosoo, David; Osei, Musah; Niare, Karamoko; & Wiru, Kenneth, et al. (2023). Background Malaria Incidence and Parasitemia during the Three-Dose RTS,S/AS01 Vaccination Series Do not Reduce Magnitude of Antibody Response nor Efficacy against the First Case of Malaria. BMC Infectious Diseases, 23(1), 716. PMCID: PMC10594884

Abstract

BACKGROUND: RTS,S/AS01 has been recommended by WHO for widespread implementation in medium to high malaria transmission settings. Previous analyses have noted lower vaccine efficacies in higher transmission settings, possibly due to the more rapid development of naturally acquired immunity in the control group.
METHODS: To investigate a reduced immune response to vaccination as a potential mechanism behind lower efficacy in high transmission areas, we examine initial vaccine antibody (anti-CSP IgG) response and vaccine efficacy against the first case of malaria (to exclude the effect of naturally acquired immunity) using data from three study areas (Kintampo, Ghana; Lilongwe, Malawi; Lambaréné, Gabon) from the 2009-2014 phase III trial (NCT00866619). Our key exposures are parasitemia during the vaccination series and background malaria incidence. We calculate vaccine efficacy (one minus hazard ratio) using a cox-proportional hazards model and allowing for the time-varying effect of RTS,S/AS01.
RESULTS: We find that antibody responses to the primary three-dose vaccination series were higher in Ghana than in Malawi and Gabon, but that neither antibody levels nor vaccine efficacy against the first case of malaria varied by background incidence or parasitemia during the primary vaccination series.
CONCLUSIONS: We find that vaccine efficacy is unrelated to infections during vaccination. Contributing to a conflicting literature, our results suggest that vaccine efficacy is also unrelated to infections before vaccination, meaning that control-group immunity is likely a major reason for lower efficacy in high transmission settings, not reduced immune responses to RTS,S/AS01. This may be reassuring for implementation in high transmission settings, though further studies are needed.

URL

http://dx.doi.org/10.1186/s12879-023-08699-7

Reference Type

Journal Article

Year Published

2023

Journal Title

BMC Infectious Diseases

Author(s)

Bell, Griffin J.
Gyaase, Stephaney
Goel, Varun
Adu, Bright
Mensah, Benedicta A.
Essone, Paulin
Dosoo, David
Osei, Musah
Niare, Karamoko
Wiru, Kenneth
Brandt, Katerina
Emch, Michael
Ghansah, Anita
Asante, Kwaku P.
Mvalo, Tisungane
Agnandji, Selidji T.
Juliano, Jonathan J.
Bailey, Jeffrey A.

Article Type

Regular

PMCID

PMC10594884

Continent/Country

Ghana
Malawi
Gabon

ORCiD

Bell, G - 0000-0003-4367-135X
Emch - 0000-0003-2642-965X
Brandt - 0000-0003-2529-7720
Goel - 0000-0002-2933-427X