I once picked up pertussis from a guy on a plane who coughed and sneezed all over me. My Tdap wasn't up to date, and I didn't know that the Tdap booster protected me against Diphtheria and Pertussis. I learned that adults don't get the violent whooping cough with Pertussis as a symptom, but that babies do and it can be fatal to them. Also: diphtheria looks and sounds like a horrific infection to have! I consider myself fortunate that haven't had a symptomatic COVID infection since the pandemic started. I look forward to getting my COVID boosters.