Great pixel style. The controls are smooth and the music is nice.
I would like to see some more feedback to the player for when you're "collecting" other virus. Like a little particle effects or screen effect.
Also, I thought it would be cool to have indicators on the edge of the screen showing where the other viruses are? Maybe something as simple as a little virus bubble that sticks to the edge of the screen in the direction of the virus. (Does that even make sense... lol)
Nice job overall. I liked it.