Masks put you at risk!!!!!, page-58

Sterile environment doesn't allow their immune system to exercise, so when it comes time for their immune system to fight off a virus, it's weak and has less ability.

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It's the analogous to an Olympic athlete beset by depression and becoming an overweight couch potato. They can't perform with the ability they once had.

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Remember whenwhen grandma told you to go out and play in the dirt?