 The lack of clear guidelines and studies addressing the proper response to the pneumococcal vaccine Pneumovax has hampered our ability to diagnosis and care for our immunodeficiency patients. Should an age matched normal response range to the Pneumovax be established, it would have a profound impact in the diagnosis, safety and care of immunodeficiency patients. Moreover, characterizing the B cell compartments response to the Pneumovax may better delineate the mechanism of protective immunity from Pneumovax and provide an additional tool for the diagnosis and care for immunodeficiency patients. 