The Quarter Pounder is back on the menu at McDonald’s. 

Last week, America’s most popular fast food chain was the target of a food safety alert sent out by the Centers for Disease Control and Prevention, which stated that the Quarter Pounders were potentially responsible for a multi-state E. coli outbreak. As Food & Wine previously reported, nearly 50 illnesses had been reported to the organization across 10 states, including 10 hospitalizations and one death connected to the outbreak. As of Oct. 24, that number grew to 75 illnesses in 13 states, with two customers developing “hemolytic uremic syndrome, a serious condition that can cause kidney failure,” according to the Food and Drug Administration (FDA). 

However, as of Sunday, the chain re-introduced the burgers to its nearly 900 restaurants affected by the outbreak, representing about 20% of all McDonald’s restaurants in the U.S. They will, however, be served with one menu item missing: Onions. 

“The issue appears to be contained to a particular ingredient and geography, and we remain very confident that any contaminated product related to this outbreak has been removed from our supply chain and is out of all McDonald’s restaurants,” Cesar Piña, the SVP, chief supply chain officer, North America, at McDonald’s, shared in a statement posted to the company’s website. 

According to the statement, the 900 restaurants involved had “historically received slivered onions from Taylor Farms’ Colorado Springs facility,” which is now under investigation by the FDA as the potential cause of the outbreak. 

“The FDA is continuing its investigation into Taylor Farms’ Colorado Springs facility,” Piña stated. “As a reminder, McDonald’s removed slivered onions from this facility from our supply chain on October 22 and shared that we had decided to stop sourcing onions from Taylor Farms’ Colorado Springs facility indefinitely. Over the past few days, you’ve likely seen that additional food service providers and restaurant brands that received onions from this facility have moved to stop selling and/or recall onions.” 

This menu change will affect McDonald’s locations in Colorado, Kansas, and Wyoming, along with some locations in Idaho, Iowa, Missouri, Montana, Nebraska, Nevada, New Mexico, Oklahoma, and Utah. Piña added in the statement the Colorado Department of Agriculture’s testing did not detect any E. coli in samples taken of Quarter Pounder beef patties, and no additional testing is planned on that ingredient.

The FDA additionally noted that symptoms of E. coli “begin anywhere from a few days after consuming contaminated food or up to nine days later” and include everything from “severe stomach cramps, diarrhea, fever, nausea, and/or vomiting.” It noted that “some infections can cause severe bloody diarrhea and lead to life-threatening conditions.” If you believe you’ve been infected, contact your healthcare provider immediately.