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Most childhood vaccines are 90–99% effective in preventing disease. Side effects are rarely serious.
A cataract is a clouding of the eyes' natural lens. As we age, some clouding of the lens may occur. The first sign of a cataract is usually blurry vision. Although glasses and other visual aids may at first help a person with cataracts, surgery may become inevitable. Cataract surgery is very successful in restoring vision, and it is the most frequently performed surgery in the United States.
Serum cholesterol testing in adults is recommended every 1 to 5 years. People with diabetes and a family history of high cholesterol should be tested even more frequently.
The horizontal fraction bar was introduced by the Arabs.
Asthma cases in Americans are about 75% higher today than they were in 1980.