They found that while stomach acids were usually enough to kill much of the bacteria, some common medications changed the equation radically. When the researchers added antacids, the bacteria in the model stomach quickly grew to a level 10 times higher than without antacids. Antacid users are now considered another "at-risk" group who should avoid raw oysters at all times.
More info on where to eat oysters in S.F and what species to look for.
Oyster Lovers Unite This Valentine’s weekend may be your best chance to eat oysters for years to come.