According to the students, this started with someone on the wrestling team--who were significantly wiped out before a tournament--and then ran through the cast of the musical last week--to the point that the assistant director was standing in for multiple parts during the last show. A couple of my students pointed the blame at specific students who came to school sick, coughing and sneezing constantly. Whatever the source(s), it's clear that students are not following the recommendations to mitigate the spread of these sorts of respiratory illness.
As most people are not testing for COVID, I don't know if that is what is going around, or if it is a strong flu, or a bit of both. As selfish as it is to say, I am quite glad that I didn't catch this bug before my Madrid trip. Hopefully (and especially considering that I'm updated on the COVID and flu vaccinations), we can sidestep it entirely.
Stay healthy out there.