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Author Question: When the immune system creates a response that is out of proportion to the threat it has been ... (Read 22 times) |
The most destructive flu epidemic of all times in recorded history occurred in 1918, with approximately 20 million deaths worldwide.
There are more nerve cells in one human brain than there are stars in the Milky Way.
Before a vaccine is licensed in the USA, the Food and Drug Administration (FDA) reviews it for safety and effectiveness. The CDC then reviews all studies again, as well as the American Academy of Pediatrics and the American Academy of Family Physicians. Every lot of vaccine is tested before administration to the public, and the FDA regularly inspects vaccine manufacturers' facilities.
When blood is exposed to air, it clots. Heparin allows the blood to come in direct contact with air without clotting.
The average adult has about 21 square feet of skin.