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).
Depression Affects Over 350 Million People Worldwide. Over 350 million people around the world have depression, according to a report issued by the World Health Organization (WHO) on World Mental Health Day (10 October). Depression is a mental disorder that undermines people's ability to function well.