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).
Major depression is rare in people over the age of 60, however, 10 to 15 percent of older people who are in hospitals and long-term care settings do have major depression. About five percent of people over the age of 65 in the United States have significant drinking problems.