How about this (/s): During a pandemic, people are hyper aware of coughing in their environment. It becomes a subconscious trigger (like a baby's cries). Every time a cough occurs in a film, it causes that same shift and elevated processing -- and has the side effect of making a viewer better pay attention/enjoy a scene.

So instead of desensitization, coughing becomes comfortable, reassuring, or perhaps even attractive due to it's being such a common part of life...hence the coughgeist may be reduced due to the appreciation of each cough.