What's the plural of virus?

I'm sick. I'm literally shivering and my teeth are chattering, and my throat hurts whenever I move my head. And I have an exam on Monday that I've barely studied for, great.
This is the second time I've been sick this January and the fourth time in the past five months, and I hate it. Not the best beginning for the new year.

In happier health-related news, my psychiatrist has me trying new antidepressants. Four days after I started taking them I could suddenly go a whole day without becoming exhausted and/or taking a nap. (Before I got sick, at least.) I'd forgotten that was possible! It feels great.