The middle of the semester is peak time for students to start getting sick.
It is also around the time that professors pile on classwork, homework and projects before the end of the semester.
While it is important to attend classes, please don't come to class when you are sick.
Sure, it's important to keep up with your classes, but it's also important to be considerate of others. If you are so sick that you cannot go more than 15 seconds without hacking up a lung or blowing your nose, please skip class. It is probably difficult for you to concentrate, but it is extremely difficult for your classmates to concentrate.
If you do decide to come to class when you are sick, plan ahead. Bring some hand sanitizer, your own tissues (so you don't have to keep getting up and walking over the people in your row) and a plastic bag to put your used tissues in.