When Exactly Did The First Covid-19 Case Emerge In China?
BEIJING, CHINA - JANUARY 21: A Chinese girl wears a protective mask as she is held by a relative as ... [+] they wait to board a train at Beijing Railway station before the annual Spring Festival on January 21, 2020 in Beijing, China. The number of cases of a deadly new coronavirus rose to nearly 300 in mainland China Tuesday as health officials stepped up efforts to contain the spread of the pneumonia-like disease which medicals experts confirmed can be passed from human to human. The number of those who have died from the virus in China climbed to six on Tuesday and cases have been reported in other parts of Asia including in Thailand, Japan, Taiwan and South Korea. (Photo by Kevin Frayer/Getty Images) Getty Images  With the help of methods used commonly in conservation science, a group of scientists estimate that the first case of Covid-19 emerged between October and mid-November 2019 in China. A new analysis published in the journal PLOS Pathogens, David Roberts from the University of Kent, U.K., and colleagues suggest the estimated date of origin was November 19. While Covid-19 continues to wreak havoc in India, Nepal, and several other countries, the quest to find answers about its origins remains elusive. Scientific evidence points towards the origins of the SARS-CoV-2 virus as a zoonotic spillover that occurred before early December 2019 before it spread globally. To dig deeper into when the first case of Covid-19 arose, the group of researchers repurposed extinction mathematical models from conservation science that were originally developed determine the date of extinction of a species, based on recorded sightings of the species. In their analysis, Roberts and colleagues 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 and territories. While the first case of Covid-19 was officially identified in December 2020, they found that it is likely that SARS-CoV-2 had spilled over into humans much earlier. Their analysis suggests that China had its first case of the respiratory disease back in early October or November 2019 before it spread globally by January 2020. These findings support growing evidence that the pandemic arose sooner and grew more rapidly than officially accepted. A previous study identified significant changes in hospital and search engine traffic in Wuhan during August to October 2019, suggesting a possible earlier existence of Covid-19, the researchers wrote in the study. A recent study conducted jointly by the World Health Organization and China on the global origin of Covid-19 also found that based on molecular evidence, their estimates place the most recent ancestor of the virus between mid-November and early December. They said the range of origin could be between late September to early December. The researchers further expanded this comparison to four other studies that identified earlier cases. Based on that, they inferred January 7, 2020, as the most likely first case in Thailand. They further estimate that the first case in France was on January 19, 2020. But the analysis estimates that the first case outside of China occurred in Japan on January 3, 2020. Whereas the first case in Europe occurred in Spain on January 12, 2020, and the first case in North America occurred in the United States on January 16, 2020. This is two weeks prior to the earliest known case of a woman identified through retrospective testing who became ill on January 31, 2020 and around six weeks before the first case was identified on February 26, 2020. The method we used was originally developed by colleague and I to date extinctions, however, here we use it to date the origination and spread of COVID-19. This novel application 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, said Roberts.