What is the chance I will get sick from eating a raw oyster?

1 in a million. Twenty million americans consume raw shellfish like clams and oysters each year. Shellfish are filter feeders that pick up and concentrate bacteria, like vibrio, from the surrounding seawater. Bacteria concentrations, and the risk or infection, is higher in warmer months. Only cooking will destroy the bacteria. There are approximately 20 vibrio vulnificans infections each year, half are fatal.