innate immunity

Yes, the nose is often the first point of initial contact with the microbial world. That was certainly the lesson of COVID and helped to explain all those nasal swabbings.
The quote was from Tom Evans, chief scientist at Oxford university’s vaccines spinout company Vaccitech The Image from the Financial Times, T-cells: the missing link in
Early in the COVID-19 pandemic, public health officials noticed something strange: Countries that still used the BCG vaccine against tuberculosis had fewer infections and deaths from coronavirus.