When did the first COVID-19 case arise?

Zootonic spillover map of early cases

Evidence is building that its origin as a zoonotic spillover occurred prior to the officially accepted timing of early December, 2019. The first case of Covid likely arose between early October and mid November 2019 in China, earlier than officially reported. 

The origins of the ongoing Covid-19 pandemic remain unclear. The first officially identified case occurred in early December 2019. Yet, this research published by PLOS Pathogens supports growing evidence that the Covid-19 pandemic arose sooner and grew more rapidly than officially reported.

Dr David Roberts‬⁩ alongside Dr Jeremy Rossman (Honorary Senior Lecturer in Virology at Kent’s School of Biosciences and President of Research-Aid Networks, Chicago) and Dr Ivan Jarić (Biology Centre of the Czech Academy of Sciences), used a statistical modelling technique previously utilised in conservation science in this new study.

‘Here we provide novel methods to date the origin of COVID-19 cases. We show that six countries had exceptionally early cases, unlikely to represent part of their main case series.’

The optimal linear estimation (OLE) modelling technique originally developed by Dr Roberts and a colleague to date extinctions of species, helped to clarify the timing of the onset of the pandemic. The researchers reversed the method to determine the date when Covid-19 most likely originated, according to when some of the earliest known cases occurred in 203 countries.

The analysis also identified when Covid-19 is likely to have spread to the first five countries outside of China, as well as other continents. For instance, it estimates that the first case outside of China occurred in Japan on 3 January 2020, the first case in Europe occurred in Spain on 12 January 2020, and the first case in North America occurred in the United States on 16 January 2020.

Dr Roberts said: ‘The novel application of OLE within the field of epidemiology offers a new opportunity to understand the emergence and spread of diseases as it only requires a small amount of data.

‘This application could be applied to provide insights into Covid-19’s continued spread and help authorities to better understand the spread of other infectious diseases in the future.’

Their research paper ‘Dating first cases of COVID-19’ is published by PLOS Pathogens. doi: 10.1371/journal.ppat.1009620

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