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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.
Interferon was scarce and expensive until 1980, when the interferon gene was inserted into bacteria using recombinant DNA technology, allowing for mass cultivation and purification from bacterial cultures.
In the United States, there is a birth every 8 seconds, according to the U.S. Census Bureau's Population Clock.
If all the neurons in the human body were lined up, they would stretch more than 600 miles.
The average human gut is home to perhaps 500 to 1,000 different species of bacteria.