Progress Is Made Battling Strep Germ By LINDSEY TANNER     CHICAGO (AP) -- Scientists say they are making headway in developing a vaccine against a common strep germ, the cause of millions of sore throats as well as a deadly but uncommon flesh-eating disease.    A test of an experimental vaccine in just 28 people prompted an immune response with no serious side effects, but it's still not known if the shot would keep people from catching the strep germ...