U.S. fast-food chains were pulling fresh onions out of their menu items on Thursday after the vegetable was named as the likely source of an E. coli outbreak at McDonald¡¯s restaurants that has sickened 49 people and killed one.

Restaurant Brands International, parent of McDonald¡¯s rival Burger King, and Yum Brands said they were removing fresh onions from menu items.

Roughly 5% of Burger King locations have removed onions from the menu, a Burger King spokesperson said in a statement.