Journal Article

Epidemiological dynamics of influenza B virus across multiple seasons in Kenya and Uganda inferred from sequence data, 2010–2021

Githinji, George, Maitland, Kathryn, Lambisia, Arnold, Nyiro, Joyce, Agoti, Charles N., Olupot-Olupot, Peter, Nyarango, Brenda K., Cheruiyot, Robinson, Makori, Timothy, Kiguli, Sarah, Owuor, D. Collins, Mutunga, Martin, Isoe, Everlyne, Katama, Esther N.

2025

Overview

Background Influenza B virus (IBV) contributes significantly to morbidity and mortality during Influenza seasons annually. However, IBV genomic surveillance occurs unevenly across the globe, particularly within the African region, obscuring its epidemiology. This study aims to elucidate the epidemiological dynamics of IBV in Kenya and Uganda between 2010 and 2022. Methods In this study, 83 near complete IBV genomes circulating in Kenya and Uganda between 2010 and 2022 were generated through Oxford Nanopore Technologies sequencing (ONT). Publicly available IBV datasets were incorporated to evaluate the public context of these genomes. Further evolutionary dynamics analysis investigated the antigenic mutation, reassortment and glycosylation patterns of IBVs circulating in Kenya and Uganda within this period. Results Alternating IBV lineage predominance and clade turnover was observed consistent with global patterns. No B/Yamagata strains were detected at the study sites after 2019. Multiple B/Victoria clade/subclades (V1A, V1A.3, V1A.3a, V1A.3a.2) and B/Yamagata clades (Y2 and Y3) were identified with no inter-lineage reassortments observed. Over time, the clades/subclades appeared to diversify through the accumulation of amino acid changes along the hemagglutinin (HA) segment backbone, especially within the known antigenic sites. Local outbreak strains appeared to be putatively introduced from both within and outside Africa. Conclusions The congruence of local and global strains in circulating lineages and amino acid changes suggests potential effectiveness of vaccines recommended for the Northern and Southern Hemispheres in East Africa.

• Publisher: BioMed Central,BioMed Central Ltd,Springer Nature B.V,BMC
• Subject: Amino acid sequence / Amino acids / Analysis / Antigens / B/Victoria / B/Yamagata / Care and treatment / Circulation / Coronaviruses / COVID-19 / Datasets / Diagnosis / Disease transmission / Epidemiology / Evolution, Molecular / Forecasts and trends / Genome, Viral / Genomes / Genomics / Glycosylation / Health aspects / Hemagglutinins / Hemispheres / Humans / IBV / Infectious Diseases / Influenza / Influenza B / Influenza B virus - classification / Influenza B virus - genetics / Influenza B virus - isolation & purification / Influenza, Human - epidemiology / Influenza, Human - virology / Internal Medicine / Japan / Kenya / Kenya - epidemiology / Medical Microbiology / Medicine / Medicine & Public Health / Morbidity / Mortality / Parasitology / Phylogenetics / Phylogeny / Pneumonia / Prevention / Risk factors / Seasons / Strains (organisms) / Time trends (Statistics) / Tropical Medicine / Uganda / Uganda - epidemiology / Vaccines