Last year I caught COVID twice. Both times I felt sick, I tested myself daily, and I was negative every time I swabbed my nostrils and nasopharynx. Both times,

Last year I caught COVID twice. Both times I felt sick, I tested myself daily, and I was negative every time I swabbed my nostrils and nasopharynx. Both times, I started swabbing any yellow mucus that I expelled, and received the positive result that I expected.