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Normal urine is sterile. It contains fluids, salts, and waste products. It is free of bacteria, viruses, and fungi.
People who have myopia, or nearsightedness, are not able to see objects at a distance but only up close. It occurs when the cornea is either curved too steeply, the eye is too long, or both. This condition is progressive and worsens with time. More than 100 million people in the United States are nearsighted, but only 20% of those are born with the condition. Diet, eye exercise, drug therapy, and corrective lenses can all help manage nearsightedness.
Most childhood vaccines are 90–99% effective in preventing disease. Side effects are rarely serious.
The average human gut is home to perhaps 500 to 1,000 different species of bacteria.
Approximately 500,000 babies are born each year in the United States to teenage mothers.