Thanks for your review and comments! You can definitely achieve 98%, most likely you were off by one part or chemical, so if you want to try again pay close attention to the hints, and for the best chance of success start off by trying 3 chemicals the first go around and check the hints later on.
You have a point about the dark/serious nature and funny symptoms. At first it felt too dark/serious and I wanted to lighten the mood to make it less bleak to play so we added in the humorous side effects - besides the entire concept of mixing random chemicals together for a vaccine is a bit silly in the first place, but I agree I think we could make it overall a bit less serious feeling.
A summary of the formula is one of the things we thought about including but just ran out of time to add. I thought about adding a clipboard or paper to the lab showing the last one used, but in its current state there's also an element of memory test to the game so it all depends on how you look at it.
Thanks again for your feeback! :)