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Most childhood vaccines are 90–99% effective in preventing disease. Side effects are rarely serious.
Intradermal injections are somewhat difficult to correctly administer because the skin layers are so thin that it is easy to accidentally punch through to the deeper subcutaneous layer.
Anti-aging claims should not ever be believed. There is no supplement, medication, or any other substance that has been proven to slow or stop the aging process.
The first-known contraceptive was crocodile dung, used in Egypt in 2000 BC. Condoms were also reportedly used, made of animal bladders or intestines.
Amoebae are the simplest type of protozoans, and are characterized by a feeding and dividing trophozoite stage that moves by temporary extensions called pseudopodia or false feet.