The world needs a proper investigation into how Covid-19 started

("Proper" is a wish. reality what we'll get is an investigation - period. A helthy dose of cynism and familiarity with historical precedent and politics predicts it will land way south of proper).

An investigation of the kind presumes human involvement. If it was just a natural mutation, a "proper investigation" is just going to fuel witch hunting and help to cause/justify conflict.

If, on the other hand, there was human involvement, if 10 parties do it and one had this accident, does it really matter which one was it? (Especially since most of them had similar, just smaller scale, accidents, in the past)? Each of those 10 could have as well done it.

Future avoidance is more about prohibiting the practice of keeping such labs and doing such experiments for military purposes (which nobody will prohibit, anyway).