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).
In Australia, it is estimated that 45 per cent of people will experience a mental health condition in their lifetime. In any one year, around 1 million Australian adults have depression, and over 2 million have anxiety.