Jan 2019: Scientists from the University of Science Technology of China collect 12 soil samples on King George Island, Antarctica, during study of penguin bacteria.
November 2019: Three workers at the Wuhan Insititue of virology fall sick with Covid-like symptoms, according to US intelligence
Dec 2019: The Arctic soil samples are sent to the Sangon Biotech laboratory in Shanghai, China, to be sequenced.
The Sangon Biotech laboratory also sequences samples from the Wuhan Institute of Virology.
Dec 2019/early 2020: The samples are analysed and during the sequencing contaminated by a different sample from another project, likely through a barcode error at the lab.
The other sample contains a mutated version of Covid-19 and genetic material from monkeys and hamsters suggesting it is from lab testing.
Virologists say the variant is a descendant of the original Wuhan strain of Covid-19. Some experts believe it is an ancestor virus that is the bridge between bat coronavirus and Covid-19.
Dec 31 2019: China confirms its first cases of Covid after reports of mystery illness spreading since November 2019.
Early 2020: The Covid sequences are uploaded to an international database with in the dataset from the Antarctic soil sample , but not exactly clear when. They go unnoticed for over a year.
Jan 2021: Researchers at Lorand University and the University of Veterinary Medicine in Hungary discover three of the Antarctic soil samples contain traces of what may be an ancestral version of Covid, along with monkey and hamster DNA.
Dec 23, 2021: The scientists publish a pre-print paper online, warning the contaminated samples could indicate the possible origin of Covid.
Jan 2022: Public access to the data is revoked after the pre-print is released and then restored a month later.
Chinese researchers at the University of Science and Technology of China, near Shanghai, said they did not ask to have the data deleted or restored.
Feb 2022: Hungarian scientists publish a second pre-print suggesting the samples may be contaminated with an early version of Covid.