If you're sick and could infect others, then you should stay home. That's the basic expectation.

But there's wiggle room - because there's also an expectation that you're an adult, you know yourself and your body better than anyone, and you're capable of making good decisions regarding your health and balancing that with your responsibilities at work.

For example, if you're a little sick but there's something you feel is very important that you need/want to finish before taking a sick day - use your best judgement. Maybe it's OK to work part of the day. Maybe it's best to stay home. Your call.