Rubella titer test positive what's that mean ?

You are immune: Once a person is immunized or had the disease, the titer (test) stays positive for life. You might be able to determine how soon before the test was done, depending upon the type of antibody test that was done. Igm usually is the marker for a recent infection. If you have a + test and had no recent symptoms (rash, fever) then i would be happy you are immune!