OysterAs oyster and other shellfish are filter-feeders and thus concentrate microorganisms in sea-water, they are easily contaminated by viruses (e.g. Hepatitis A and Norwalk-like viruses). Consumption of undercooked oyster with viruses contaminated poses a high risk of virus infection and thus may cause illness.

Assurance of food safety relies on tri-partite collaboration among government, food trade and the general public. Food trade is responsible for selling safe food and food handlers should always aware of ensuring consumers' food safety. In the preparation of oyster (e.g. deep-fried oyster, braised oyster with ginger and spring onion, and braised oyster with port) food handlers are recommended to observe environmental and utensils hygiene. Food handlers are also reminded to take the following precautions: