The US officials confirmed that details of some of the earliest samples of coronavirus in China that were in an American database were removed. The data was first submitted to the US-based Sequence Read Archive last year in March. Three months later, the same researcher requested the data “to be withdrawn”, said the US National Institutes of Health (NIH) in a statement on Wednesday.

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The genetic sequences originated from the Chinese city, Wuhan, where first case of COVID-19 was found in 2019. The reason stated for its withdrawal at the time was that the sample information had been updated and would be submitted to another database, said the agency. The researcher asked for the withdrawal “to avoid version control issues”, reported Bloomberg.

“Submitting investigators hold the rights to their data and can request withdrawal of the data”, said the agency. “NIH can’t speculate on motive beyond the investigator’s stated intentions”. Jesse Bloom, an American virologist who publicised earlier in the week that the samples were missing, said that the disappearance of the sequences from the database raises doubts over whether or not more things from the outbreak in Wuhan had been shielded. After recovering the data, he said that it had not provided conclusive details on how or where the virus originated, reported Bloomberg.

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US President Joe Biden called for American intelligence agencies to probe the matter again, while China strongly denied about the Wuhan lab having any link to the outbreak.