The Centers for Disease Control and US Food and Drug Administration (FDA) have concluded their investigation into 2024's E coli outbreak linked to McDonald's Quarter Pounder hamburgers.
The authorities have determined that there is no longer a public health threat.
The outbreak, initially reported on 22 October, led to at least 104 people falling ill across 14 states, with 34 hospitalisations, as reported by abcNews.
One fatality occurred in Colorado and four individuals developed a severe kidney disease complication.
The FDA, alongside the US Centers for Disease Control and Prevention (CDC) and state health departments, identified raw yellow onions from Taylor Farms in California as the likely source.
The onions were used in Quarter Pounders at McDonald’s outlets in Colorado, Kansas and Wyoming, among others.
According to the CDC, no new cases have been reported since 21 October, which coincides with McDonald's decision to remove the Quarter Pounder from menus in the impacted states.
Taylor Farms issued a voluntary recall of the yellow onions on 22 October.
Despite extensive testing by federal and state health officials in Colorado, the specific strain of E coli was not detected in onion samples or environmental tests. However, evidence pointed to the recalled onions as the probable cause of the outbreak.
In response to the outbreak, McDonald's temporarily withdrew Quarter Pounders from 3,000 stores nationwide before reducing this number to 900 after identifying the onions as the source of contamination.
The company has since found an alternative onion supplier and has resumed sales of Quarter Pounders with slivered onions.
In mid-November, the fast-food giant disclosed plans to invest $100m to attract customers back to its restaurants, with $65m earmarked for supporting franchisees most affected by the outbreak.
McDonald's did not provide current sales figures for the affected regions but expressed gratitude to US regulators for their swift response and reiterated its commitment to stringent food safety protocols.
This has been McDonald's most significant food safety concern since 2018 when 500 customers suffered intestinal illnesses after consuming salads from its outlets.
