Amid a deadly E. coli outbreak linked to McDonald’s Quarter Pounders, Burger King and Yum Brands are pulling fresh onions from some of their own locations.

Yum is yanking the topping from some KFC, Pizza Hut and Taco Bell locations “out of an abundance of caution,” Yum said Thursday in a statement to CBS News. Yum did not specify the locations impacted. “We will continue following supplier and regulatory guidance to ensure the ongoing safety and quality of our food,” a spokesperson for Yum said.

Burger King said it has asked the 5% of its locations that received onions from a Taylor Farms Colorado facility to dispose of them two days ago. “We are in the process of restocking them from other facilities,” according to a spokesperson.

The fast-food chain has not heard from health authorities and has not received any indications of illness, the Burger King spokesperson added.

The developments come two days after the federal health officials said an E. coli outbreak likely tied to onions used on McDonald’s Quarter Pounders had sickened at least 49 people in 10 states, killing one. McDonald’s removed the product from about a fifth of its 13,000 U.S. locations as federal and state health officials work to confirm the source of the bacteria. 

As most of those stricken reported eating McDonald’s Quarter Pounder burgers, investigators are working to figure out if slivered onions or beef patties are behind the outbreak. 

McDonald’s locations in Colorado, Kansas, Utah, Wyoming and parts of Idaho, Iowa, Missouri, Montana, Nebraska, Nevada, New Mexico and Oklahoma have temporarily stopped selling Quarter Pounders. 

McDonald’s identified California-based produce giant Taylor Farms as the supplier for the sliced onions the company removed.

Taylor Farms told CBS News Colorado Wednesday night it conducted tests on “raw and finished products” and “found no traces of E. coli.”

Still, Taylor Farms Colorado removed yellow onions from the market produced out of its Colorado facility, it said. 

Most of those stricken in the outbreak live in Colorado and Nebraska, with 26 sickened in the former and nine stricken in the latter, according to the U.S. Centers for Disease Control and Prevention. Of the 26 who became ill in Colorado, one older adult died, the CDC said. Health officials in Utah and Wyoming each reported four illnesses. Other states reporting illnesses include Iowa, Kansas, Missouri, Oregon and Wisconsin.  

At least 10 people have been hospitalized, including a child with hemolytic uremic syndrome (HUS), a serious condition that can cause kidney failure, according to the CDC.  The illnesses began at the end of September, and the most recent incident occurred October 11. 

It typically takes three to four weeks to determine if a sick person is part of an outbreak. Those infected with the toxin-producing E. coli experience severe stomach cramps, diarrhea and vomiting, and most recover without treatment after five to seven days.