Concept is fun, but quite repetitive and could gain from some variation from run to run. Controls are a bit unintuitive, I spent the first run wandering why I couldn't control my alien before understanding that you don't have to hold the arrow but to repeatedly press in a direction to be able to move.
It looks nice and feels polish.
I think the link with the theme is a bit weak. I understand the idea of pandemic waves from your narrative but it doesn't reflect in gameplay. Maybe with way more kittens, densely packed, with shorter infection time, such that actual waves propagate from kitten to kitten would have been cool.
Overall it is fun to play for a few minute but quickly becomes too simple to get you involved and to make you want to come back.