We had that over the summer actually. One was sick and mom kept him home on the Monday but he came to daycare on the Tuesday. She ended up keeping him home the Wednesday/Thursday (likely shouldn't have been here on the Tuesday either) and it spread like wildfire. That Friday and the following weeks after that I had kids sick. I managed to get it too (worked anyways even with a fever). So glad we are all better now. It was a long 2 months of sickness.