With a nice and simple mechanic, Sneeze Fest is really easy to understand and get started with. The levels get progressively harder, until it becomes sort of a puzzle game. The thing I like the most about the game is honestly the theme. You basically go around and infect people on purpose, why the hell not!
Something I would try and do is maybe emphasize the puzzle aspect a bit more. Potentially give the first character a longer timer, or even no timer at all, so the player has some time to figure out the level beforehand. Rather than having to play the level twice/thrice before understanding it. That being said this could be a design decision.
Next to this, I noticed that some characters have different amount of time to infect the others. This could be different sprites. Perhaps a big, bulky guy has a lot more time than a smaller guy?
One other small remark I had is that the UI that shows how many people are left sometimes blocks the view of the player itself.
Other than that, I think you guys did an amazing job overall! Keep it up!