SARS-CoV-2 Omicron variant of concern in the Seychelles: Introduction and spread

Background: The emergence of the Omicron variant of concern in late 2021 led to a resurgence of SARS-CoV-2 infections globally. By September 2022, Seychelles had experienced two major surges of SARS-CoV-2 infections driven by the Omicron variant. Here, we examine the genomic epidemiology of Omicron in the Seychelles between November 2021 and September 2022. Methods: : We analysed 618 SARS-CoV-2 Omicron genomes identified in the Seychelles between November 2021 and September 2022 to infer virus introductions and local transmission patterns using phylogenetics and the ancestral state reconstruction approach. We then evaluated the impact of government coronavirus 2019 (COVID-19) countermeasures on the estimated number of viral introductions during the study period. Results: : The genomes classified into 43 distinct Pango lineages. The first surge in Omicron cases (beginning November 2021 and peaking in January 2022) was predominated by the BA.1.1 lineage (59%) co-circulating with 11 other Omicron lineages. In the second surge (between April and June 2022), four lineages (BA.2, BA.2.10, BA.2.65 and BA.2.9) co-circulated and these were swiftly replaced by BA.5 subvariants in July 2022, which remained predominant through to September 2022. In the latter period, sporadic detections of BA.5 subvariants BQ.1, BE and BF were observed. We estimated 109 independent Omicron importations into Seychelles over the 11-month period, most of which occurred between December 2021 and March 2022 when strict government restrictions (SI>50%) were still in force. The districts Anse Royale, and Baie St. Anne Praslin appeared to be the major dispersal points fuelling local transmission. Conclusions: : Our results suggest that the waves of Omicron infections in the Seychelles were driven by multiple lineages and multiple virus introductions. The introductions were followed by substantial local spread and successive lineage displacement that mirrored the global patterns.

How prepared is the world? Identifying weaknesses in existing assessment frameworks for global health security through a One Health approach.

The COVID-19 pandemic has exposed faults in the way we assess preparedness and response capacities for public health emergencies. Existing frameworks are limited in scope, and do not sufficiently consider complex social, economic, political, regulatory, and ecological factors. One Health, through its focus on the links among humans, animals, and ecosystems, is a valuable approach through which existing assessment frameworks can be analysed and new ways forward proposed. Although in the past few years advances have been made in assessment tools such as the International Health Regulations Joint External Evaluation, a rapid and radical increase in ambition is required. To sufficiently account for the range of complex systems in which health emergencies occur, assessments should consider how problems are defined across stakeholders and the wider sociopolitical environments in which structures and institutions operate. Current frameworks do little to consider anthropogenic factors in disease emergence or address the full array of health security hazards across the social-ecological system. A complex and interdependent set of challenges threaten human, animal, and ecosystem health, and we cannot afford to overlook important contextual factors, or the determinants of these shared threats. Health security assessment frameworks should therefore ensure that the process undertaken to prioritise and build capacity adheres to core One Health principles and that interventions and outcomes are assessed in terms of added value, trade-offs, and cobenefits across human, animal, and environmental health systems.

Detection of SARS-CoV-2 variant 501Y.V2 in Comoros Islands in January 2021 (preprint)

Phylogenetic analysis of six SARS-CoV-2 genomes collected from the Comoros islands confirmed local circulation of the 501Y.V2 variant of concern during the countrys first major SARS-CoV-2 wave in January 2021. These findings demonstrate the importance of SARS-CoV-2 genomic surveillance and have implications for ongoing COVID-19 control strategies on the islands.