Here's how I'm approaching this, right or wrong. And I'm certainly not saying it's right for anybody but me.
1. This is still a lottery ticket. As with all lottery tickets, there's a small chance you get rich and a chance you end up with nothing. Maybe when all is said and done you just end up with your money back. But unlike the lottery, at least we all have individual control over every step between rich and $0.
2. When we bought in and this was still sub-$1 and nobody knew what COVID was, the base case from the CFO in that first conference call was, in his words, a conservative estimate of a $10 share price if they hit their target portion of the TAM for HIV. JUST HIV. They're filed for HIV, cancer is looking more promising now than it was then, and oh by the way, maybe COVID. So to me, that $10 point is the one at which I start to consider whether I want my basis back. That's NOT the right decision for everyone. It's not the way I was thinking about it in the beginning, but it's the way I've been thinking about it for some time now.
3. I'm still following
@chet's lead on all this. His thoughts matter. He's closer to it than the rest of us. If something changes in his mind, and he makes us all aware of it, then it's worth our consideration, too. His confidence means something if you've been here for a long time. To me, at least.
4. Is it worth still buying in the $3s?

My basis is sub-$1. I identified a max amount I was willing to buy in for up front, and I'm there. Now, since the shares are worth considerably more, it's made me comfortable at the points the stock dips into the $2s to buy more, wait for it to get back into the $3s, and sell off 80% to recoup the basis on JUST those shares. So, I'm accumulating (effectively) small tranches of additional $0 basis shares. That's only slightly more risk than I wanted to take to do so. I'm good with it. Is taking that risk right for someone who has no other shares and wants in? Maybe? My feeling is there's money to be made here, but it's tougher sledding the rest of the way. Just don't overextend yourself. You wouldn't spend your mortgage payment on lottery tickets. See #1.