PPIB and hepatitis A virus infection: In both solid tumor and hematological malignancy subgroups, all values were significantly lower than literature rates of expected antibody retention, except for mumps CCS with hematological malignancies had the lowest rates of seropositivity with protective antibodies in only 70% (14/20) of measles, 61.5% (8/13) of mumps, 75% (12/16) of rubella, 31.25% (5/16) of varicella, 40% (6/15) of tetanus, and 23% (3/13) of hepatitis B titers.