In pure red cell aplasia, does peripheral blood-positive IgG for parvovirus have significance if persistently positive on retesting, but IgM and PCR are negative?

The patient has a recurrence of the disease despite tapering prednisone and cyclosporine. Bone marrow exams x2 without MDS. Testing for all other causes of secondary PRCA is negative. Is the IgG just an incidental finding, and this should be treated as primary/idiopathic PRCA?