Two E. Coli outbreaks linked to Chipotle restaurants appear to be over, officials said Monday.

The Centers for Disease Control and Prevention (CDC) said it still doesn’t know what specific ingredient was behind the outbreaks, though it hasn’t received word of any illnesses since Dec. 1.

The CDC said 60 people in 14 states fell ill last October and November, and 22 were hospitalized. The organization interviewed 59 of those people, and 52 of them said they had eaten at Chipotle.

The CDC collected food from several Chipotle restaurants, though none of its tests showed signs of the bacteria. The organization said a food source is only identified in 46 percent of outbreaks, and it can be hard to determine the exact item responsible for the illnesses in cases where restaurants cook several ingredients together and serve them in different menu items.

According to the CDC, the first E. Coli outbreak affected 55 people in Washington, Oregon, California, Delaware, Illinois, Kentucky, Maryland, Minnesota, New York Ohio and Pennsylvania. The second outbreak, which featured a different strain of the bacteria, sickened five people in Kansas, Oklahoma and North Dakota. None of the 60 people died or developed hemolytic uremic syndrome, a type of kidney failure that sometimes occurs following E. Coli infections.

Chipotle has said it has since implemented new food safety protocols, and announced earlier this month that it will close all of its restaurants for four hours on Feb. 8 for a food safety meeting.

The outbreaks were just a part of the recent struggles for Chipotle.

The restaurant also told investors earlier this month that it was subpoenaed by a federal grand jury in connection with an “isolated norovirus incident” in August at a California restaurant. The same message indicated a norovirus outbreak in December at a Boston restaurant “worsened the adverse financial and operating impacts” Chipotle experienced from the E. Coli outbreaks.

Norovirus and E. Coli are both foodborne illnesses that can cause vomiting, diarrhea and stomach cramps, according to the CDC.

Chipotle’s stock was trading at $750.42 on Oct. 13, near an all-time high, but tumbled to $404.26 on Jan. 12 amid the E. Coli and norovirus concerns. That was a 54 percent drop.

The stock has rebounded slightly and was trading at $472.64 on Monday afternoon.