McDonald's plans to return the Quarter Pounder to its menu, after determining that the beef patties it uses for the burger were not the source of a recent deadly E. coli outbreak.

According to The New York Times, McDonald's conducted tests on samples of the burger meat from two suppliers that provided beef to the 900 locations affected by the outbreak across 12 states. Instead, the Centers for Disease Control believes that the E. coli likely came from the raw slivered onions inside the Quarter Pounder, with McDonald's stating on October 25 that it planned to stop buying onions from Taylor Farms, a large regional supplier based out of Colorado Springs. Around that same time, Taylor Farms said that it had recalled several yellow onion products, over fears of possible E. coli contamination.

On October 27, McDonald's announced that it would be putting the Quarter Pounder back on the menu in the states affected by the outbreak, while noting that the burger will no longer include slivered onions in those areas. Taco Bell, KFC, Pizza Hut and Burger King locations in those regions have also stopped including onions with their respective menu offerings as a precautionary measure. In total, it's estimated that the McDonald's E. coli outbreak sickened 75 people between September 27 and October 10, and led to the death of one person in Colorado.