Clinical, Genomic, and Immunological Characterization of RSV Surge in Sydney, Australia, 2022

Abstract

OBJECTIVES: The 2022 seasonal respiratory syncytial virus (RSV) epidemic in Sydney, Australia saw an unprecedented number of RSV detections. We aimed to characterize genomic and immunologic factors associated with the surge in RSV cases. METHODS: Whole genome sequences of RSV were generated from 264 RSV-infected infants and linked to case-matched clinical data from the 2022 southern hemisphere RSV season. We then performed an immunologic analysis of baseline RSV-specific humoral immunity in women of childbearing age before and throughout the coronavirus disease 2019 pandemic. RESULTS: Clinical analysis revealed a high burden of disease across patients of all health backgrounds. More than one-half of RSV-related health care visits by infants resulted in hospitalization, and one-quarter required high-flow respiratory support or a higher level of care. Viral phylogenetic analyses revealed that 2022 Sydney RSV sequences were closely related to viruses that had been circulating globally since 2017, including those detected in recent US outbreaks. Nonsynonymous mutations within the palivizumab and nirsevimab binding sites were detected at low frequencies. There was no difference in baseline RSV-neutralizing antibody titers between 2020 and 2022. CONCLUSIONS: Collectively, these findings suggest that neither the emergence of a novel RSV genotype nor hypothesized immune debt was associated with the surge of RSV cases and hospitalizations in 2022. Continued genomic and immunologic surveillance is required to further understand the factors driving outbreaks of RSV globally, and to inform guidelines for the rollout and ongoing use of recently developed immunotherapeutics and vaccines.

RSV Disease Threat and Innovative Prevention Methods in Health Protection: A Review

“…In 2022, the number of RSV cases in the state of New South Wales was about four times higher than in 2021. Similarly, large seasonal outbreaks of RSV were accompanied by increased hospitalizations in the northern hemisphere during the same period [16].…”

Prevention and Potential Treatment Strategies for Respiratory Syncytial Virus

“…One significant advanatage of this drug over palizumab is that it requires only one shot, rather than five monthly shots for palizumab, which greatly reduces the cost. It has recently been approved by the U.S. Food and Drug Administration (FDA) [36].…”

Increased pediatric RSV case counts following the emergence of SARS-CoV-2 are attributable to increased testing

“…However, increased age has not been mechanistically tied to an immunity debt, and was also observed among children diagnosed in 2020 14 , the year in which the debt was supposedly accumulating. While two studies have identified a decline in RSV-targeting IgG concentrations during the pandemic 15,16 , another study found no change in neutralizing antibody titers, 17 such that the clinical or epidemiological relevance of this decline is unclear. The alternative “immunity theft” hypothesis posits that COVID-19 infections weakened our immune response to other pathogens.…”