Introductions and early spread of SARS-CoV-2 in France, 24 January to 23 March 2020

Abstract

Following SARS-CoV-2 emergence in China, a specific surveillance was implemented in France. Phylogenetic analysis of sequences retrieved through this surveillance suggests that detected initial introductions, involving non-clade G viruses, did not seed local transmission. Nevertheless, identification of clade G variants subsequently circulating in the country, with the earliest from a patient who neither travelled to risk areas nor had contact with travellers, suggests that SARS-CoV-2 might have been present before the first recorded local cases.

Tracking the onset date of the community spread of SARS-CoV-2 in western countries

“…Some studies traced the onset date of the largest SARS-CoV-2 community transmission clusters to around early February in Italy and Spain, mid-February in Washington State and New York city (NYC), and from late February onwards in Belgium and the United Kingdom (UK). 11 , 12 , 13 , 14 , 15 , 16 , 17 These results supports that rapid interventions prevented onward transmission of early symptomatic imported cases detected in Europe and the USA in January 2020 and that community outbreaks were seeded by unnoticed introductions occurred after detection of first travel-associated cases. 12 , 16 , 18 Other genomic studies, however, support a period of undetected community spreading of SARS-CoV-2 since mid-January 2020 in Europe, late January or early February 2020 in the USA (Washington and Illinois) and early or mid-February 2020 in Brazil.…”

“… 11 , 12 , 13 , 14 , 15 , 16 , 17 These results supports that rapid interventions prevented onward transmission of early symptomatic imported cases detected in Europe and the USA in January 2020 and that community outbreaks were seeded by unnoticed introductions occurred after detection of first travel-associated cases. 12 , 16 , 18 Other genomic studies, however, support a period of undetected community spreading of SARS-CoV-2 since mid-January 2020 in Europe, late January or early February 2020 in the USA (Washington and Illinois) and early or mid-February 2020 in Brazil. 13 , 19 , 20 , 21 , 22 , 23 According to these studies, community outbreaks in Europe and the Americas were seeded by unnoticed viral introductions that probably occurred before detection of first travel-associated cases and long before description of the firsts cases of community transmission.…”

“…Genomic data shown that for some places the epidemic was mostly driven by few local predominant lineages (e.g., Spain, New York and Brazil), while for others it was probably seeded by a high number of importation events and no predominant lineage was identified so far (e.g., Belgium, Germany, Netherlands and the UK). 11 , 13 , 14 , 16 , 17 , 19 , 22 , 23 To estimate the beginning of domestic spread in these locations, we made the TN10 and TN100 projections. The onset date of community transmission of SARS-CoV-2 was traced back to between late January and early February by the TN10 projections and to between early and mid-February by the TN100 projections ( Fig.…”

Differential serological and neutralizing antibody dynamics after an infection by a single SARS-CoV-2 strain

“…Data were analyzed according to the bio-informatic protocol developed by the Artic consortium. Both patients were infected by the same strain, its sequence harboring 7 SNPs compared to the reference genome Wuhan/Hu-1/2019 (NCBI Nucleotide—NC_045512, GenBank—MN908947) and belonging to the G3b phylum [ 9 ], thus carrying the recently identified D614G mutation [ 10 ]. On August 1st and 2nd, 2020, the two sequences were deposited on the GISAID platform with accession ID EPI_ISL_505003 and EPI_ISL_506041 for patient 1 and 2 respectively.…”

Knowledge and Perception of COVID-19 Pandemic During the First Wave (Feb-May 2020): a Web Based Survey Among Italian Healthcare Workers

“…This culminated in a national lockdown declared on March 10 th , 2020 and ended on May 3 rd , 2020. COVID-19 is spread by human-to-human transmission through droplets and direct contact; it has an incubation period of 2-14 days [8][9][10][11][12][13].…”