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After a vasectomy, it takes about 12 ejaculations to clear out sperm that were already beyond the blocked area.
The most destructive flu epidemic of all times in recorded history occurred in 1918, with approximately 20 million deaths worldwide.
The familiar sounds of your heart are made by the heart's valves as they open and close.
Most childhood vaccines are 90–99% effective in preventing disease. Side effects are rarely serious.
Women are 50% to 75% more likely than men to experience an adverse drug reaction.
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