Deadly Flu and the WHO

In this recent article from the AP we the people are informed that a lab in Ohio sent a deadly strain of the flu virus out to labs in the US and all over the world. The 1957 version apparently killed between 1 million and 4 million people. (Let's ignore the fact that a variant of 3 million people is ridiculous and almost criminal in its inaccuracy.)Apparently this version of the flu has not been included in vaccinations since 1968, so most of us carry no immunity to it. This makes it extremely worrisome. How do things like this happen? According to the writer, bioterrorism has been ruled out. So that leaves an in house error as the only explanation. This was a huge mistake for a major biotech company to make. Aren't they supposed to be trained not to make mistakes like this? Maybe they passed off a list of samples to someone and had them arbitrarily choose what sample to send out. It frightens me to see that the fate of the world might some day be in the hands of a lowly intern with a spreadsheet.