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Most childhood vaccines are 90–99% effective in preventing disease. Side effects are rarely serious.
When blood is exposed to air, it clots. Heparin allows the blood to come in direct contact with air without clotting.
Cancer has been around as long as humankind, but only in the second half of the twentieth century did the number of cancer cases explode.
Cocaine was isolated in 1860 and first used as a local anesthetic in 1884. Its first clinical use was by Sigmund Freud to wean a patient from morphine addiction. The fictional character Sherlock Holmes was supposed to be addicted to cocaine by injection.
Approximately 15–25% of recognized pregnancies end in miscarriage. However, many miscarriages often occur before a woman even knows she is pregnant.