And why do they believe that?
not 100% sure, but the evidence suggests that they did
I do know they were working on it
did they mutate it to make it more dangerous? probably, but we are unlikely to ever know for sure
did it come from there lab? absolutely
did they lie about it and its effects? 100% yes
the main reason I think they did engineer this disease (IE - mutate it to make it more dangerous) is the fact that they accused us and Italy of engineering it
why would they do that unless they are worried that someone will prove it was man-made or at least man-enhanced?sure looks like they were trying to get ahead of the issue and create uncertainty about who to blame...
From what I have read about virus mutations is that we are a long way from a designer virus. For example, you might be able select a mutant virus with a stronger protein shell so it would be harder to destroy but that shell is likely to make it harder to invade cells. Scientist have seen untold numbers of mutations over the years but none have proved to be invincible and most of them can not function and thus cease to exit. Even if a mutated virus could be produced that would be more resilient, having a faster incubation period, and other characteristics which would make it more deadly, there is always the problem of containment. If a virus is deadly to your enemies, it also deadly to you and your allies. As we have seen viruses have no problem crossing boarders.
IMHO, accident unleashing a dangerous biological agent is much more probably and dangerous.
You are making some faulty assumptions there.
You're assumption is that one nation or the other would make this to attack this nation or that, sure, then such thinking would not make sense.
On the other hand, what if all the elites, of every nation were in on it? What if the only thing they wanted to do was to create a one world government where there would no longer be any say for the little people on how they would have control over their lives, and the people in charge of their own nations would forever have their families in charge of them?
If the only purpose is to slightly sicken folks, to make them dependent, frightened, and enslaved to the elites healthcare systems? I think this virus has done precisely what it was meant to do.
This is a bio-weapon targeted at the world's productive citizen and free citizen, no matter which nation they live in.