I'm not sure what the take-home from this is. Fewer people called in sick. Does that mean more people who were actually sick were tricked into a false feeling

I'm not sure what the take-home from this is. Fewer people called in sick. Does that mean more people who were actually sick were tricked into a false feeling of health and went into work to spread their germs? Or does it mean that healthy people that were just feeling a bit groggy were re-invigorated by a cold shower?