The immune response of the body is suppressed by cytotoxic drugs. The effectiveness of the vaccine may be poor and generalized infection may occur in patients immunized with live.
Since the cytotoxic drugs are immunosuppressants, the response of the body to immunization is reduced. A study in 53 patients with Hodgkins disease showed that chemotherapy reduced the antibody response 60% when measured three weeks after immunization with a pneumo-coccal vaccine. The patients were treated with mustine, vm-cristine, prednisone and procarbazine. A few of them also had bleomycin, vinblastine or cyclophosphamide. Subtotal radiotherapy reduced the response a further 15%. The response to influenza immunization in children with various malignancies was also found to be markedly suppressed by chemotherapy. The cytotoxic drugs used were mercap-topunne, methotrexate, vincnshne and predmsone. Some of them were also treated with vincristine, actmomycin and cyclophosphamide.
Immunization with live vaccines may result in a potentially life-threatening infection. For example, a woman who was under treatment with 15 mg methotrexate daily for psoriasis and who was vaccinated against smallpox, developed a generalized vaccinial infection. Studies in animals given smallpox vaccine confirmed that they were more susceptible to infection if treated with methotrexate, mercaptopunne or cyclophosphamide. Smallpox is no longer a problem, but other live vaccines such as rubella, measles, mumps and others continue to be used. Extreme care should therefore be exercised in immunizing patients with live vaccines who are receiving cytotoxics or other immunosuppressive treatment.