After months of scary headlines and millions of flu shots, could swine flu finally be on the downswing? According to a new study of some 170,000 flu tests by researchers at Quest Diagnostics, the illness peaked in April and reached a second peak in October before beginning to decline. "Between this peak week and December 9, testing rates fell by 75 percent. In the most recent week reported, December 9, testing rates were equivalent to volumes experienced in late August, when the second wave began," the company said. The largest declines were among patients in Pennsylvania, Maryland, Delaware, the District of Columbia, and Virginia and West Virginia, a region that saw an 87 percent decline in testing rates in the same period. Researchers attribute the drop to a combination of vaccinations and patients gaining resistance through prior infection.