OK, so this one definitely is good news, but is going to need some explaining:
We have
multiple virulence reducing RNA deletions confirmed in the virus. Now, these variants aren't going to magically solve the problem - they're all less able to spread than the variants that they're mutations of. However, this is a big deal for a few reasons:
1. Given how little testing we've done for these things, this strongly suggests that there are a
lot of these kinds of deletions out there. That is: we're rolling the dice lots of times.
2. Deletions don't undo themselves: RNA (unlike DNA) simply has no mechanism for correcting for gene deletions (there isn't a second copy available to re-construct it from), so these deletions will hang around, and potentially stack with more such deletions. That is: these dice stack.
Those two combine to mean that the odds of what I'm going to say below aren't as tiny as you might thing.
3. None of these examples have any effect on immune response. That is: if you're immune to one, you're immune to all of them.
4. If we isolate a reliably non-lethal variant of the virus, we have a new exit strategy (other than natural herd immunity, vaccination, or (local) eradication): variolation. Given a version of the virus that consistently doesn't kill people (and preferably consistently doesn't make them significantly ill), we could intentionally spread it through the (low-risk) population, therefore getting herd immunity without ever having to have the lethal version of the virus spread.
Now, this isn't guaranteed by any means (it's honestly relatively unlikely, even given points 1 and 2), and there's essentially nothing that we can do to speed it up (other than making sure that we're checking the RNA of as many different virus samples as possible for deletions, so that we don't miss them when they do happen), but it's an extra set of dice to roll, along with all of the vaccine candidates.
There's also evidence that it's [url=https://www.medrxiv.org/content/10.1101/2020.03.16.20037259v1]becoming less deadly over time.