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Reports of a mysterious pneumonia spreading in Wuhan, China first emerged in late December 2019. After spreading rapidly throughout the city over the following weeks, the disease spread throughout worldwide, with the first US case emerging on Jan.19.
The revelations in the article by CDC researchers reinforce the growing understanding that the coronavirus was circulating silently around the world earlier than expected and could reignite debate over the origins of the pandemic.
This is not the first evidence showing that the virus could have existed or infected people outside of China before 2020. A patient in France contracted the virus after being hospitalized with flu-like symptoms at the end of December , contradicting official statistics showing Covid-19 arrived in the country returning from Wuhan at the end of January.
The CDC study found antibodies to the coronavirus in 39 samples from California, Oregon and Washington as early as December 13 through December 16.
Antibodies were also found in early January in 67 samples from Connecticut, Iowa, Massachusetts, Michigan, Rhode Island and Wisconsin – before the virus was known to have been introduced to those places.
Scientists said the antibodies were unlikely to have developed to curb other coronaviruses, as 84 samples were found to have specific SARS-CoV-2 neutralizing activity.
They also noted that it was not possible to determine the extent of infections at the national or state level based on the samples, or whether cases were transmitted locally or related to travel.
The results were published in the journal Clinical infectious diseases.