The U.S. government announced on Tuesday that it has concluded its investigation into a recent E. coli outbreak associated with McDonald’s Quarter Pounder hamburgers, affirming that there is no longer a threat to food safety.

The outbreak, which emerged in late October, led to illnesses in at least 104 individuals across 14 states. Among those affected, 34 required hospitalization, and one person from Colorado tragically lost their life. Additionally, four individuals experienced severe complications related to kidney disease.

The U.S. Food and Drug Administration (FDA), alongside the Centers for Disease Control and Prevention (CDC) and state health agencies, traced the outbreak back to yellow onions supplied by Taylor Farms, a California-based company. These onions were served raw on Quarter Pounders in various McDonald’s locations, including those in Colorado, Kansas, Wyoming, and more. Following the outbreak, Taylor Farms initiated a voluntary recall of the yellow onions on October 22.

Investigations by federal and state health officials in Colorado revealed no traces of the particular E. coli strain in the onions examined, nor in any environmental samples. Despite this, their findings indicated that the recalled yellow onions were likely responsible for the outbreak.

In a statement released on Tuesday, the FDA confirmed that “McDonald’s is no longer serving recalled onions and there does not appear to be a continued food safety concern related to this outbreak.”

In response to the outbreak, McDonald’s temporarily removed Quarter Pounders from 20% of its U.S. locations. The fast-food chain quickly sought out an alternative supplier and has since resumed offering Quarter Pounders with slivered onions at all U.S. establishments as of last month.

However, the aftermath of the outbreak has impacted customer demand significantly. In mid-November, McDonald’s announced plans to allocate $100 million to entice customers back into their restaurants. This initiative includes $65 million aimed specifically at supporting franchisees who were most adversely affected by the outbreak.