Authorities in the Netherlands fear hundreds of people could be infected with hepatitis A after eating frozen blueberries from the country's largest supermarket chain, Albert Heijn.

As of Jan. 14, at least 12 people, aged between 25 and 77, had been confirmed infected. The products contained in one-kilogram bags of frozen blueberries have since been removed from shelves.

A spokesperson for the National Institute of Public Health (RIVM) said on Tuesday that the reported infections are only severe cases in which people sought medical help. "We believe there may be hundreds of infections,” the spokesperson said. 

According to health authorities, the first patient appeared at the end of November last year, but the number of cases has increased. So, the RIVM started an investigation that led to the discovery that blueberries were linked to these cases. The Netherlands Food and Products Authority (NVWA) took samples and found contamination with hepatitis A.

Albert Heijn issued a safety warning on Monday regarding 1-kilo bags of its own-brand frozen blueberries due to possible hepatitis A contamination. The company recalled the products from its freezers and asked customers to throw away any blueberries they had or return the bags to get their money back.

These are bags with an expiration date of 14-04-2026, but, as a precaution, the supermarket chain removed all one-kilo bags from the shelves.

According to Albert Heijn, the contaminated blueberries come from a manufacturer in Poland.

Hepatitis A is a disease that usually causes mild symptoms, such as fatigue, abdominal pain, and jaundice. Still, it can be deadly and can enact an inflammation of the liver amid more worrying symptoms, particularly in those with weak immune systems or other concurrent health issues.