Viral Lineages in the 2022 RSV Surge in the United States

   In autumn 2022, an unusually early surge in respiratory syncytial virus (RSV) infections was observed across the United States. Whole-genome sequencing of 105 residual diagnostic specimens from symptomatic patients in the Boston area revealed that the surge was driven by a mix of multiple preexisting RSV-A (91%) and RSV-B (9%) lineages, rather than by a single, highly transmissible variant. Genomic analysis showed RSV-A genomes grouped into at least 10 clades, all belonging to GA2.3.5, while RSV-B genomes were genotype GB5.0.5a. These clades were shared across geographically disparate regions (e.g., Washington State), and their estimated times of most recent common ancestor ranged from 2014 to 2017 for RSV-A and from 2016 for RSV-B. Coinfections with rhinovirus, enterovirus, and metapneumovirus were also noted. The findings suggest that the surge was likely influenced by nonviral factors such as altered population immunity due to COVID-19 pandemic interventions.

   In autumn 2022, an unusually early surge in respiratory syncytial virus (RSV) infections was observed across the United States. Whole-genome sequencing of 105 residual diagnostic specimens from symptomatic patients in the Boston area revealed that the surge was driven by a mix of multiple preexisting RSV-A (91%) and RSV-B (9%) lineages, rather than by a single, highly transmissible variant. Genomic analysis showed RSV-A genomes grouped into at least 10 clades, all belonging to GA2.3.5, while RSV-B genomes were genotype GB5.0.5a. These clades were shared across geographically disparate regions (e.g., Washington State), and their estimated times of most recent common ancestor ranged from 2014 to 2017 for RSV-A and from 2016 for RSV-B. Coinfections with rhinovirus, enterovirus, and metapneumovirus were also noted. The findings suggest that the surge was likely influenced by nonviral factors such as altered population immunity due to COVID-19 pandemic interventions.