"Some of the features (potentially) look engineered," a leading infectious disease expert wrote of his early look at the Covid-19 virus in an email to Dr. Anthony Fauci in January of last year. That email has been seized on by some as a smoking gun, proving that top officials and scientists covered up the origins of the virus. On its own, the email doesn’t prove that or any other conclusions. But it does raise questions about why scientists appeared to brand any suggestion of a potential Chinese cover-up of the virus origins as out of bounds.