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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.
Warfarin was developed as a consequence of the study of a strange bleeding disorder that suddenly occurred in cattle on the northern prairies of the United States in the early 1900s.
When blood is exposed to air, it clots. Heparin allows the blood to come in direct contact with air without clotting.
There are more nerve cells in one human brain than there are stars in the Milky Way.
On average, someone in the United States has a stroke about every 40 seconds. This is about 795,000 people per year.

