I found this on babycentre.com but most pregnancy books contain the just about the same information. I have eaten cooked shellfish a few times already. I have no plans to stop unless my MD tells me otherwise!
"Oysters and other shellfish should be avoided during pregnancy, unless they are part of a hot meal and have been thoroughly cooked. This is because, when they are raw, these types of seafood might be contaminated with harmful bacteria and viruses that can cause food poisoning. Pregnant women are particularly susceptible to food poisoning because pregnancy suppresses their immune systems. The bacteria and viruses are usually killed by proper cooking making these shellfish safe to eat."
"For clams, mussels, and oysters, watch for the point at which their shells open, which indicates that they're done. Throw out those that remain closed after cooking. "
As an FYI: "Pregnant women should avoid eating shark, swordfish and marlin altogether because of the high levels of mercury in these fish, which could harm your baby's developing nervous system. You also need to limit how much tuna you eat as this also contains relatively high amounts of mercury "
Hmm, that is a good question. I pretty sure the vodka sauce is fine because like you said the alcholol is cooked out of it, but I'm not sure about the mussels.
I ate mussels several times cooked of course from restaurants. Also, I ate a ton of vodka sauce, one of my favorites :) Mine was from a jar, ha ha. I'm sure it's just fine.