Q: Can Raw Onion Prevent the Flu?
A: There is no scientific evidence that a cut raw onion absorbs germs or rids the air of toxins/poisons.
A wives tale that dates back as far as the 1500’s claims that placing a cut raw onion in rooms throughout a residence could protect its occupants from getting the bubonic plague.
Long before germs were discovered, the dominate belief was contagious diseases were spread by miasma, or “noxious air.”
While false, this belief remained part of folk medicine through the 19th century claiming to ward off epidemics like smallpox, influenza, and other “infectious fevers.”
Good Morning Gloucester 
Have heard that as well
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