Has there ever been a hastily arranged mass 'virus' vaccination experiment on the world's population?The simple answer is no, it hasn't.
The longer answer is it almost certainly hasn't. Some viruses can cause other conditions to be triggered, Auto immune conditions especially but those are fairly rare. Vaccines however haven't been seen to do that ever, not in the 100 years plus of mass vaccination.
And on a 'virus' that looks more and more likely to be man made/engineered!