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Basic Characteristics of Mutations
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Mutation Site
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G24368T |
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Mutation Site Sentence
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Clade 20C dominated the first wave (20C: 908/1;684, 54%, 20B: 438/1;684, 26%, 20A: 263/1;684, 16%), and 800 of 1;684 (48%) Swedish sequences formed a country-specific 20C cluster defined by a spike mutation (G24368T). |
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Mutation Level
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Nucleotide level |
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Mutation Type
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Gene/Protein/Region
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S |
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Standardized Encoding Gene
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S
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Genotype/Subtype
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20C |
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Viral Reference
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MN908947
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Functional Impact and Mechanisms
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Disease
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COVID-19
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Immune
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- |
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Target Gene
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-
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Clinical and Epidemiological Correlations
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Clinical Information
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- |
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Treatment
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- |
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Location
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Sweden |
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Literature Information
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PMID
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39392000
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Title
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Early unrecognised SARS-CoV-2 introductions shaped the first pandemic wave, Sweden, 2020
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Author
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Dyrdak R,Hodcroft EB,Broddesson S,Grabbe M,Franklin H,Gisslen M,Holm ME,Lindh M,Nederby-Ohd J,Ringlander J,Sundqvist M,Neher RA,Albert J
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Journal
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Euro surveillance : bulletin Europeen sur les maladies transmissibles = European communicable disease bulletin
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Journal Info
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2024 Oct;29(41):2400021
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Abstract
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BackgroundDespite the unprecedented measures implemented globally in early 2020 to prevent the spread of SARS-CoV-2, Sweden, as many other countries, experienced a severe first wave during the COVID-19 pandemic.AimWe investigated the introduction and spread of SARS-CoV-2 into Sweden.MethodsWe analysed stored respiratory specimens (n = 1,979), sampled 7 February-2 April 2020, by PCR for SARS-CoV-2 and sequenced PCR-positive specimens. Sequences generated from newly detected cases and stored positive specimens February-June 2020 (n = 954) were combined with sequences (Sweden: n = 730; other countries: n = 129,913) retrieved from other sources for Nextstrain clade assignment and phylogenetic analyses.ResultsTwelve previously unrecognised SARS-CoV-2 cases were identified: the earliest was sampled on 3 March, 1 week before recognised community transmission. We showed an early influx of clades 20A and 20B from Italy (201/328, 61% of cases exposed abroad) and clades 19A and 20C from Austria (61/328, 19%). Clade 20C dominated the first wave (20C: 908/1,684, 54%; 20B: 438/1,684, 26%; 20A: 263/1,684, 16%), and 800 of 1,684 (48%) Swedish sequences formed a country-specific 20C cluster defined by a spike mutation (G24368T). At the regional level, the proportion of clade 20C sequences correlated with an earlier weighted mean date of COVID-19 deaths.ConclusionCommunity transmission in Sweden started when mitigation efforts still focused on preventing influx. This created a transmission advantage for clade 20C, likely introduced from ongoing cryptic spread in Austria. Therefore, pandemic preparedness should have a comprehensive approach, including capacity for large-scale diagnostics to allow early detection of travel-related cases and community transmission.
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Sequence Data
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OQ816151-OQ816755;OQ818825;OQ818826;OR864025-OR864222;OR940528-OR940682
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