It's winter and most of us will be sick at one point or another this season. Make sure that illness does not become an excuse for bad behavior. We can not expect best behavior when any being is not feeling well. However, sickness is never an reason for bad behavior. Continue with consequences you have in place for undesirable behavior, even when a being is sick.
When a small being is sick, set the bar lower for their behavior. Don't ask them to do as much as they normally do. Maybe that means that you need to do the cleaning up even if they usually help.
When they start to feel better, make sure to raise the bar back up.