I was sick most of my freshman year. Went to school halfway across the country. Entirely new set of viruses versus what I was used to.

Happens to people who move to different countries too.

Common enough in basic training that it's got a nickname as well. https://afwm.org/life-during-bmt/bmt-illnesses/

I'm convinced I nearly died during my first semester. Swine flu, pneumonia and a throat infection all in the course of a month. Anyone who thinks this won't spread through a college doesn't have a clue.