Plausible Date for SARS-CoV-2 Host Jump into Humans
This thread discusses the plausible date for the host jump of SARS-CoV-2 into humans. Evidence suggests that the first case reported in China dates back to 17 November, from a Hubei Province (Wuhan) resident aged 55. The first reported case from Europe is a 42 year-old man with no known link to China or any recent history.
Prof Francois Balloux
Director @UGI_at_UCL. Interest in Infectious disease epidemiology, pathogen genomics and global health Mastodon account: @FBalloux@genomic.social
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A thread about the plausible date for the host jump of SARS-CoV-2 into humans. A lot has been published about this, but not all the claims are robust. Below, I'm listing the evidence I personally find believable.
— Prof Francois Balloux (@BallouxFrancois) June 22, 2023
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The first case reported in China dates back to 17 November, from a Hubei Province (Wuhan) resident aged 55 (this case was never officially confirmed, but also never denied)
— Prof Francois Balloux (@BallouxFrancois) June 22, 2023
2/https://t.co/Ffut3fzxfC -
The first reported case from Europe is a 42 year-old man with no known link to China or any recent history of international travel, presenting in a French hospital on 27 December 2019.
— Prof Francois Balloux (@BallouxFrancois) June 22, 2023
3/https://t.co/lG0GcLiucn -
There have been multiple papers reporting positive serological results for SARS-CoV-2 as early as summer 2019. False positive are common in serological surveys and to me the earliest plausible evidence is from Northern Italy from mid December 2019 on.
— Prof Francois Balloux (@BallouxFrancois) June 22, 2023
4/https://t.co/mqw1J2nNsy -
Phylogenetic reconstructions of the earliest common ancestor tend to point to October-Dember 2019. We estimated the jump of SARS-CoV-2 into humans to ~24 November 2019 (95% CI: 6 October 2019 – 11 December 2019).https://t.co/lDbQX4YpL7
— Prof Francois Balloux (@BallouxFrancois) June 22, 2023
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This estimate assumes that a single lineage of SARS-CoV-2 jumped into humans.
— Prof Francois Balloux (@BallouxFrancois) June 22, 2023
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Also this estimate is probable slightly biased towards a more recent emergence. The earliest cases were sampled retrospectively, but we used 'raw' collection dates. Taking this delay into account might push back the point estimate by ~1-2 weeks.
— Prof Francois Balloux (@BallouxFrancois) June 22, 2023
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Under the assumption of multiple host jumps into humans, Pekar et al. obtained an estimate around 18 November 2019 (23 October to 8 December), largely in line with the former but with a narrower confidence interval.
— Prof Francois Balloux (@BallouxFrancois) June 22, 2023
8/https://t.co/FMYpHMVz0C -
The evidence listed in this thread is based on three independent approaches (direct, serology and phylogenetics), but is highly consistent and points to a host jump of SARS-CoV-2 into humans around November 2019.
— Prof Francois Balloux (@BallouxFrancois) June 22, 2023
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The evidence also fits a scenario of an initial emergence in China, followed by rapid transmission to Europe, with Northern Italy having acted as the epicentre of the spread to the rest of the world.https://t.co/lDbQX4YXAF pic.twitter.com/V94Is3CmD9
— Prof Francois Balloux (@BallouxFrancois) June 22, 2023 -
There's nothing new in this thread but I felt it may be worthwhile summarising the available evidence again, as it provides a framework for discussions evaluating the significance of WIV personnel being among the earliest known cases, assuming this were to be confirmed.
— Prof Francois Balloux (@BallouxFrancois) June 22, 2023
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