You hit the nail on the head.
As George Carlin once said, your immune system needs germs to practice on.
People who masked and huddled in doors because they were scared of the big, bad virus have significantly compromised immune systems.
For example...take your average NFL football team and put them on bedrest for two seasons. Then stick them into a game and see what happens.
” your immune system needs germs to practice on.”
I like it! I might grab it for a tagline.