The NIH deleted in June 2020 some early SARS-CoV-2 genetic sequences at the request of the Chinese researcher who had previously submitted them.

It is not obvious what those sequences would prove if they were still available, but given the way China operates, we have to suspect that officials ordered the researcher to "request" their deletion, and that the purpose was to impede understanding. I think the NIH should change its rules for deletions. Perhaps it should allow the submitter to add notes, such as "I now suspect this was spurious", but not actual deletion.