If you get fresh shrimp and wash them good, they're safe. Fish, likewise, are eaten raw. Raw oysters from polluted waters or during red tides are not safe unless cooked. Not many folks are as lucky as I in gathering their food. When thawed, they are just like fresh.
Fish get the same treatment whether boated or bought.
I normally buy oysters by the sack, eat until I and all around are stuffed. Grill a few. Put the rest in a recyled whiskey barrel with salty water and eat them over the next few weeks. As for beef, I don't trust store ground beef for burgers and rarely buy it for any reason. I catch chuck cheap and grind my own.