It's well made, with nice UI and effects – and I certainly appreciate the viruses don't move along straight lines which makes it less predictable. But all in all, it's also very repetitive; i.e. the gameplay when you start the game is exactly the same as the gameplay after one minute.

The trajectory of the viruses also doesn't even initially incline towards your position, so there can be long periods of time in which you sit in the middle and do nothing. I usually lost because I became complacent after twenty seconds of doing nothing, and then I got one-shotted by a fast-moving virus.
I'm not saying they should all be aimed at you (as that would make the game impossible), but consider slightly (or by a random percentage) tilting their initial trajectory towards your position.

It's a good game to play for a couple of minutes, but there's not a lot of reasons to keep playing for a higher score. Perhaps consider introducing new things later on, or add medals/scoreboard to attract more players and make them compete with each other: https://www.newgrounds.io/