Very little search effort turns up plenty of evidence of risks: https://www.vdh.virginia.gov/epidemiology/epidemiology-fact-...

"What are the symptoms of illnesses that can result from eating contaminated raw oysters or clams?

The illnesses of most concern from eating raw or undercooked oysters or clams are Vibrio infection, norovirus infection, and hepatitis A. See fact sheets for those diseases for more details.

Symptoms can include vomiting, diarrhea, nausea, stomach pains, severe weakness. Vibrio infections can also cause skin rashes and blisters, shaking chills, and high fever. Hepatitis A can cause yellowing of the skin or whites of the eyes. Some of the illnesses can be quite serious and require quick medical attention."