MILWAUKEE (AP) — The federal government has given conditional approval to the first vaccine licensed to fight a deadly pig virus, and warmer weather appears to be slowing the spread of the disease that has been blamed in part for making bacon more expensive.

Porcine epidemic diarrhea has killed millions of baby pigs since it showed up in the United States last year, and pork prices have been rising for months. Bacon averaged more than $6 per pound in May, nearly 19 percent more than it did 12 months earlier, according to the U.S. Bureau of Labor Statistics.