It has, but a mediocre coder can change the source code and re-release in literally minutes. It just slowed the spread a bit. Everything out there is not spreading, but I guarantee a new version without the kill switch has been released by now.
It is literally e-Ebola.
Only if the “victim” deliberately French kisses the virus.
There are dozens of ransomware programs in the e-universe.
Just don't download attachments from strangers or click on websites you haven't heard about before.
And install some good security software.
McAfee scans every attachment before I open it for the first time, and it disables every email link that connects to a suspicious website (you have to manually re-enable the link if you know the website is safe).
For people that are STILL using XP, which MS long ago stopped supporting because it is so old. It's kinda like thinking the "3 second rule" of eating dropped food works in a subway bathroom.😝