From the Canadian Public Health agency - "As of March 30, 2022, there have been 279 cases of norovirus and gastrointestinal illness linked to consumption of B.C. oysters reported in the following provinces: B.C. (262), Alberta (1), Saskatchewan (1), and Ontario (15). Individuals became sick between mid-January and late March 2022, and no deaths have been reported. Although not all cases of illness have been tested, testing of several cases has confirmed the presence of a norovirus infection."
Oysters are filter feeds and is Norovirus gets into the water, it can be picked up by the oysters. Eating contaminated oysters can result in illness, especially when eaten raw.
https://www.fda.gov/food/alerts-advisories-safety-information/fda-advises-restaurants-and-retailers-not-serve-or-sell-potentially-contaminated-raw-oysters-canada
FDA Advises Restaurants and Retailers Not to Serve or Sell Potentially Contaminated Raw Oysters from Canada (April 2022)
https://www.fda.gov/food/alerts-advisories-safety-information/fda-advises-restaurants-and-retailers-not-serve-or-sell-potentially-contaminated-raw-oysters-canada
FDA Advises Restaurants and Retailers Not to Serve or Sell Potentially Contaminated Raw Oysters from Canada (April 2022)
