The Food and Drug Administration upgraded a recall of frozen blueberries and mixed berries sold at Publix grocery stores across the U.S. to the highest health risk level on Tuesday, according to an enforcement report. 

Publix on July 29 announced a recall of four varieties of frozen GreenWise organic blueberries and mixed berries sold at stores across eight states over potential E. coli contamination. The FDA is now categorizing it as a “Class 1” recall, which the agency assigns to product recalls “in which there is a reasonable probability that the use of or exposure to a violative product will cause serious adverse health consequences or death.”

Twelve people infected with the outbreak strain of E. coli have been reported in two states, according to the Centers for Disease Control and Prevention. No deaths linked to the outbreak have been reported. 

The following products, shipped to Publix stores in Alabama, Florida, Georgia, Kentucky, North Carolina, South Carolina, Tennessee and Virginia, are under recall. They should be discarded or returned to Publix for a full refund. Their expiration dates are before Feb. 9, 2028.

• GreenWise Organic Whole Blueberries, 10-ounce, UPC 41415-06453
• GreenWise Organic Whole Blueberries, 48-ounce, UPC 41415-12053
• GreenWise Organic Whole Mixed Berries, 10-ounce, UPC 41415-06753
• GreenWise Organic Whole Mixed Berries, 48-ounce, UPC 41415-12153

E. coli, a large group of bacteria, can cause illness characterized by severe stomach cramps, diarrhea and vomiting, according to the FDA. In severe cases, the bacteria can cause hemolytic uremic syndrome, which can lead to kidney failure and be life-threatening. 

Last week, the FDA also upgraded an egg recall to the highest health risk level over potential salmonella contamination.