Since elementary school, I've had one major pet peeve. Everyone's experienced it. Maybe you've done it. But someone with the flu, or a cold, or something else, go to school and manages to sneeze and cough and half-die all over the classroom. If you're really unlucky, they don't cover their mouth when they cough and sneeze. It's irritating at that moment. Maybe you forget about it for a day or two. And then you get sick. And you know exactly why you're sick. You know exactly who the reason is. And it could all have been avoided if the aforementioned person hadn't gone to class sick.
I get why people go to school sick. They don't want to miss class. This is especially true in University, where missing class could leave you without notes that you need for an upcoming exam. Some professors even have pop quizzes that count for a significant percentage of your grade. And I think the system should be more lenient for these situations. But in my opinion, I think it's not worth risking the health of your classmates for some notes.
At the very least, please take a Dayquil to minimize coughing. You'll also feel better. And cover your mouth. Keep it covered.