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Most childhood vaccines are 90–99% effective in preventing disease. Side effects are rarely serious.
In 1864, the first barbiturate (barbituric acid) was synthesized.
Only one in 10 cancer deaths is caused by the primary tumor. The vast majority of cancer mortality is caused by cells breaking away from the main tumor and metastasizing to other parts of the body, such as the brain, bones, or liver.
Signs of depression include feeling sad most of the time for 2 weeks or longer; loss of interest in things normally enjoyed; lack of energy; sleep and appetite disturbances; weight changes; feelings of hopelessness, helplessness, or worthlessness; an inability to make decisions; and thoughts of death and suicide.
The average human gut is home to perhaps 500 to 1,000 different species of bacteria.