Abstract Details
Name
Kinetics of rotavirus-specific IgA and IgG at an individual and population level in Malawi
Presenter
Jonathan Mandolo, Malawi Liverpool Wellcome Trust
Co-Author(s)
Jonathan Mandolo1,2, Marc Y. R. Henrion1,2, Martha Moyo1, Leah Mulira1, Willy Wotcheni1, Fatima Mtonga1, Memory Mvula1, Nigel A. Cunliffe3,7, Kayla G. Barnes1,5,6, Kondwani C. Jambo1,2,4*, Khuzwayo C. Jere1,3,4* 1Malawi Liverpool Wellcome Programme, Blantyre, Malawi. 2Department of Clinical Sciences, Liverpool School of Tropical medicine, L3 5QA, Liverpool, UK. 3Clinical Infection, Microbiology and Immunology, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK. 4Medical Laboratories Department, Kamuzu University of Health Sciences, Blantyre, Malawi. 5Broad Institute of the Massachusetts Institute of Technology (MIT) and Harvard, Cambridge, MA 02142, USA. 6Department of Tropical disease biology and Vector Biology, Liverpool School of Tropical medicine, L3 5QA, Liverpool, UK. 7National Institute for Health and Care Research Health Protection Research Unit in Gastrointestinal Infections, University of Liverpool, Liverpool, UK.
Abstract Category
Vaccines
Abstract
Background
Oral rotavirus vaccine effectiveness is lower in low- and middle-income countries than in high-income countries, partly due to interference from maternal-derived rotavirus-specific IgG antibodies. These antibodies decline over time, reaching a level that impairs their ability to impact vaccine immunogenicity. We aimed to estimate the optimal vaccination window for improved immunogenicity in Malawi, a high rotavirus disease-burdened setting.
Methods
Longitudinal sera was collected from 84 infants over one year at five-time points (January 2021 to October 2023) and one-time point cross-sectional sera from 798 healthy individuals (December 2022 to June 2024). We measured rotavirus-specific IgG and IgA antibodies using ELISA. We extracted rotavirus gastroenteritis case data from our surveillance database from December 2022 to June 2024.
Results
Results showed that maternal-derived rotavirus-specific IgG levels were lower in seropositive infants compared to seronegative ones (4820.2 IU/ml vs. 1001.01 IU/ml, p=0.015). Infants with the lowest maternal antibody levels were 5 times more likely to be seropositive (OR=5.83, p=0.012). An exponential decay model indicated that the median IgG concentration crossed the seropositivity threshold at 6.2 months. Population data revealed that IgG levels declined until reaching a nadir at 8.4 months, coinciding with a peak in severe rotavirus gastroenteritis. Rotavirus-specific IgA peaked at 9 months and correlated with a decline in severe cases between 9 and 17 months.
Conclusion
Our findings suggest that administering a booster rotavirus vaccine at 6 months – when maternal antibody levels are at their lowest and rotavirus cases peak – could be an optimal strategy to enhance immunogenicity.
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