There are currently more than 750 such areas in the National Wilderness Preservation System comprising over 109 million acres -- roughly 5% of the United States by area. Need a refresher from the other 95%? The Active Times picked 10 wild places in the lower 48 states that are truly wild.
Polio, which struck children disproportionately, could attack the central nervous system and cause muscle deterioration, paralysis and even death. American virologist Jonas Salk, who was born 100 years today on October 28, 1914, developed the worldâs first safe and effective polio vaccine.
Oral polio vaccine (OPV) is an attenuated vaccine, produced by the passage of the virus through non-human cells at a sub-physiological temperature, which produces spontaneous mutations in the viral genome.Oral polio vaccines were developed by several groups, one of which was led by Albert Sabin.n November 2013, the World Health Organization announced a polio outbreak in Syria. In response, the Armenian government put out a notice asking Syrian Armenians under age 15 to get the polio vaccine.