If someone has the flu, yes stay home. Granted they say covid is 10x more contagious than flu, but if you Go around like you dont care and someone else gets sick? Their blood is on your hands.
Granted BH we have a vaccine that brings flu numbers down every year. But nonetheless if you’re careless, and around others, I’d say if someone even misses going to learning torah because some careless person passed them the flu- their missed Torah learning is on your hands too (the original careless infected person)