Key result
HRSV BA-7AA variant spreads globally without distinct phylogenetic clustering, peaking at ~27% of BA genotypes.
Why the study?
Limited data are available on the epidemiology and transmission dynamics of the HRSV BA-7AA variant with a 7-amino-acid extension in the G protein.
Observational (n=501)
This study establishes a basis for forecasting and warning of the reemergence of BA-7AA variants associated with severe cases and outbreaks.
What is already known about this topic?Human respiratory syncytial virus variant with a 7amino-acid extension in the G protein of the BA genotype (BA-7AA) is associated with severe neonatal pneumonia outbreak, high intensive care unit occupancy and death.However, limited data are available on the epidemiology and transmission dynamics of the BA-7AA variants. What is added by this report?This study integrated publicly available sequences of the second hypervariable region of the G gene of the BA-7AA variant with those sequenced in this study to clarify the emergence and transmission dynamics of the BA-7AA variant.What are the implications for public health practice?By revealing the circulation of the BA-7AA variant, this study established a basis for forecasting and warning of the reemergence of BA-7AA variants associated with severe cases and outbreaks.
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Song et al. (2026) conducted an observational in Human respiratory syncytial virus (HRSV) infection (n=501). HRSV BA-7AA variant was evaluated on Global circulation and phylogenetic clustering of the BA-7AA variant. The HRSV BA-7AA variant emerged in 2013 and spread to 33 countries by 2024, peaking in 2016 when it accounted for 27.0% of BA genotypes, with no distinct phylogenetic clusters over time or region.
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