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Approximately 70% of expectant mothers report experiencing some symptoms of morning sickness during the first trimester of pregnancy.
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.
Malaria was not eliminated in the United States until 1951. The term eliminated means that no new cases arise in a country for 3 years.
As the western states of America were settled, pioneers often had to drink rancid water from ponds and other sources. This often resulted in chronic diarrhea, causing many cases of dehydration and death that could have been avoided if clean water had been available.