OPV has been the vaccine of choice for controlling poliomyelitis in many countries, and for the global polio eradication initiative, because of the ease of oral administration, its superiority in conferring intestinal immunity in immunologically naive individuals, and its low cost.
Persistent depressive disorder, or PDD, (formerly called dysthymia) is a form of depression that usually continues for at least two years. Affects approximately 1.5 percent of the U.S. population age 18 and older in a given year. (about 3.3 million American adults).
Rural areas have a higher share of aging residents, with more health problems, and more limited access to health services than urban areas. Additionally, DHHS reports indicate that approximately 20% of U.S. residents aged 55+ have a mental disorder, including depression, which has been shown to be highly related to suicide attempts and completions.