The 2022 RSV surge was driven by multiple viral lineages

Abstract

The US experienced an early and severe respiratory syncytial virus (RSV) surge in autumn 2022. Despite the pressure this has put on hospitals and care centers, the factors promoting the surge in cases are unknown. To investigate whether viral characteristics contributed to the extent or severity of the surge, we sequenced 105 RSV-positive specimens from symptomatic patients diagnosed with RSV who presented to the Massachusetts General Hospital (MGH) and its outpatient practices in the Greater Boston Area. Genomic analysis of the resulting 77 genomes (54 with >80% coverage, and 23 with >5% coverage) demonstrated that the surge was driven by multiple lineages of RSV-A (91%; 70/77) and RSV-B (9%; 7/77). Phylogenetic analysis of all US RSV-A revealed 12 clades, 4 of which contained Massachusetts and Washington genomes. These clades individually had times to most recent common ancestor (tMRCA) between 2014 and 2017, and together had a tMRCA of 2009, suggesting that they emerged well before the COVID-19 pandemic. Similarly, the RSV-B genomes had a tMRCA between 2016 and 2019. We found that the RSV-A and RSV-B genomes in our sample did not differ statistically from the estimated clock rate of the larger phylogenetic tree (10.6 and 12.4 substitutions per year, respectively). In summary, the polyphyletic nature of viral genomes sequenced in the US during the autumn 2022 surge is inconsistent with the emergence of a single, highly transmissible causal RSV lineage.

Resurgence of respiratory syncytial virus with dominance of RSV-B during the 2022–2023 season

“…Whole-genome sequencing and phylogenetic analysis of 47 RSV-B sequences indicated that the GB5.0.5a and GB5.0.6a genotypes (both equivalent to the BA strains) were responsible for the 2022-2023 outbreak. The 2022-2023 RSV-B surge was also driven by GB5.0.5a in the United States (Adams et al, 2023), Austria (Redlberger-Fritz et al, 2021, Italy (Tramuto et al, 2023), and other countries (Jallow et al, 2023). Molecular analysis of RSV G genes revealed the presence of a 60-nucleotide duplication in HVR2, which is a landmark characteristic of BA strains initially described in Buenos Aires, Argentina, in 1999.…”

Clinical validation of an RSV neutralization assay and testing of cross-sectional sera pre- and post- RSV outbreaks from 2021-2023

“…Patients with no reported RSV infection might have experienced unreported RSV infection from the smaller outbreak of winter 2021, potentially inflating neutralizing titers and confounding comparison of pre-and post-2022 outbreak populations. RSV strains A2 and B WV/14617/85, classically used for FRNT and PRNT validation [24], were used instead of more contemporary and/or clinical isolates in circulation during the 2022-2023 pandemic [59][60][61].…”

Temporal Shift of the Respiratory Syncytial Virus Epidemic Peak for the Years 2020–2023 in Marseille, Southern France

“…More interestingly, they found that this lineage was already circulating before the COVID-19 pandemic and that it was not a new, more virulent emerging lineage. A study in the state of Massachusetts in the Boston [ 26 ] area also reported a surge in RSV cases and genomic studies showed that this increase in RSV was due to the co-circulation of RSV-A and RSV-B, with a clear predominance of RSV-A (91%) over RSV-B (9%). Finally, we have not analyzed the potentially associated viral co-infections for RSV-positive patients.…”