If you want to try other antivirus software to see if they can get the job done, here are some options that I know of (of course, I don’t know very much about computer viruses, so I’m sure there are better tools out there).
I use Microsoft’s Windows Defender, and it works well for me, though I’ve been lucky enough to never need to remove a virus from my computer, so I can’t attest to how well it works for that… But it’s a full-fledged free antivirus software for PC, and if you have Windows you should already have it on your computer. I believe you need to turn off your Avira before you turn on Windows Defender—from what I understand, you can only have one antivirus software running on a computer at any time; two or more, they’ll interfere with each other. Here’s a download link in case it’s not on your computer: https://www.microsoft.com/en-us/windows/windows-defender
Microsoft’s Malicious Malware Removal Tool has a subset of malware it scans for. It’s designed to be downloaded and run once, and is for any malware that’s currently “active” (is that the term?) on the device. It updates every month. It doesn’t get rid of viruses that aren’t “active,” and it doesn’t protect from viruses, but it also won’t stomp on any antivirus software you’re currently using. It’ll just run once and then get out of the way. If it finds and removes the worm, great! If not, then you’ll have to find something a bit meatier: https://www.microsoft.com/en-us/download/malicious-software-removal-tool-details.aspx
Another option is a Free Trial of Malwarebytes. The antivirus protection only runs for 14 days, but the software will always be able to detect and remove malware (and rootkits, it says, if that’s applicable here?) that have already gotten onto the computer. I know a friend who got a nasty piece of malware on their computer, and they used the Malwarebytes Free Trial to get rid of it. From what I gathered, it worked well: https://www.malwarebytes.com/premium/